/* * CDDL HEADER START * * The contents of this file are subject to the terms of the * Common Development and Distribution License (the "License"). * You may not use this file except in compliance with the License. * * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE * or http://www.opensolaris.org/os/licensing. * See the License for the specific language governing permissions * and limitations under the License. * * When distributing Covered Code, include this CDDL HEADER in each * file and include the License file at usr/src/OPENSOLARIS.LICENSE. * If applicable, add the following below this CDDL HEADER, with the * fields enclosed by brackets "[]" replaced with your own identifying * information: Portions Copyright [yyyy] [name of copyright owner] * * CDDL HEADER END */ /* * Copyright 2009 Sun Microsystems, Inc. All rights reserved. * Use is subject to license terms. */ /* * Kernel task queues: general-purpose asynchronous task scheduling. * * A common problem in kernel programming is the need to schedule tasks * to be performed later, by another thread. There are several reasons * you may want or need to do this: * * (1) The task isn't time-critical, but your current code path is. * * (2) The task may require grabbing locks that you already hold. * * (3) The task may need to block (e.g. to wait for memory), but you * cannot block in your current context. * * (4) Your code path can't complete because of some condition, but you can't * sleep or fail, so you queue the task for later execution when condition * disappears. * * (5) You just want a simple way to launch multiple tasks in parallel. * * Task queues provide such a facility. In its simplest form (used when * performance is not a critical consideration) a task queue consists of a * single list of tasks, together with one or more threads to service the * list. There are some cases when this simple queue is not sufficient: * * (1) The task queues are very hot and there is a need to avoid data and lock * contention over global resources. * * (2) Some tasks may depend on other tasks to complete, so they can't be put in * the same list managed by the same thread. * * (3) Some tasks may block for a long time, and this should not block other * tasks in the queue. * * To provide useful service in such cases we define a "dynamic task queue" * which has an individual thread for each of the tasks. These threads are * dynamically created as they are needed and destroyed when they are not in * use. The API for managing task pools is the same as for managing task queues * with the exception of a taskq creation flag TASKQ_DYNAMIC which tells that * dynamic task pool behavior is desired. * * Dynamic task queues may also place tasks in the normal queue (called "backing * queue") when task pool runs out of resources. Users of task queues may * disallow such queued scheduling by specifying TQ_NOQUEUE in the dispatch * flags. * * The backing task queue is also used for scheduling internal tasks needed for * dynamic task queue maintenance. * * INTERFACES ================================================================== * * taskq_t *taskq_create(name, nthreads, pri_t pri, minalloc, maxall, flags); * * Create a taskq with specified properties. * Possible 'flags': * * TASKQ_DYNAMIC: Create task pool for task management. If this flag is * specified, 'nthreads' specifies the maximum number of threads in * the task queue. Task execution order for dynamic task queues is * not predictable. * * If this flag is not specified (default case) a * single-list task queue is created with 'nthreads' threads * servicing it. Entries in this queue are managed by * taskq_ent_alloc() and taskq_ent_free() which try to keep the * task population between 'minalloc' and 'maxalloc', but the * latter limit is only advisory for TQ_SLEEP dispatches and the * former limit is only advisory for TQ_NOALLOC dispatches. If * TASKQ_PREPOPULATE is set in 'flags', the taskq will be * prepopulated with 'minalloc' task structures. * * Since non-DYNAMIC taskqs are queues, tasks are guaranteed to be * executed in the order they are scheduled if nthreads == 1. * If nthreads > 1, task execution order is not predictable. * * TASKQ_PREPOPULATE: Prepopulate task queue with threads. * Also prepopulate the task queue with 'minalloc' task structures. * * TASKQ_THREADS_CPU_PCT: This flag specifies that 'nthreads' should be * interpreted as a percentage of the # of online CPUs on the * system. The taskq subsystem will automatically adjust the * number of threads in the taskq in response to CPU online * and offline events, to keep the ratio. nthreads must be in * the range [0,100]. * * The calculation used is: * * MAX((ncpus_online * percentage)/100, 1) * * This flag is not supported for DYNAMIC task queues. * This flag is not compatible with TASKQ_CPR_SAFE. * * TASKQ_CPR_SAFE: This flag specifies that users of the task queue will * use their own protocol for handling CPR issues. This flag is not * supported for DYNAMIC task queues. This flag is not compatible * with TASKQ_THREADS_CPU_PCT. * * The 'pri' field specifies the default priority for the threads that * service all scheduled tasks. * * void taskq_destroy(tap): * * Waits for any scheduled tasks to complete, then destroys the taskq. * Caller should guarantee that no new tasks are scheduled in the closing * taskq. * * taskqid_t taskq_dispatch(tq, func, arg, flags): * * Dispatches the task "func(arg)" to taskq. The 'flags' indicates whether * the caller is willing to block for memory. The function returns an * opaque value which is zero iff dispatch fails. If flags is TQ_NOSLEEP * or TQ_NOALLOC and the task can't be dispatched, taskq_dispatch() fails * and returns (taskqid_t)0. * * ASSUMES: func != NULL. * * Possible flags: * TQ_NOSLEEP: Do not wait for resources; may fail. * * TQ_NOALLOC: Do not allocate memory; may fail. May only be used with * non-dynamic task queues. * * TQ_NOQUEUE: Do not enqueue a task if it can't dispatch it due to * lack of available resources and fail. If this flag is not * set, and the task pool is exhausted, the task may be scheduled * in the backing queue. This flag may ONLY be used with dynamic * task queues. * * NOTE: This flag should always be used when a task queue is used * for tasks that may depend on each other for completion. * Enqueueing dependent tasks may create deadlocks. * * TQ_SLEEP: May block waiting for resources. May still fail for * dynamic task queues if TQ_NOQUEUE is also specified, otherwise * always succeed. * * NOTE: Dynamic task queues are much more likely to fail in * taskq_dispatch() (especially if TQ_NOQUEUE was specified), so it * is important to have backup strategies handling such failures. * * void taskq_wait(tq): * * Waits for all previously scheduled tasks to complete. * * NOTE: It does not stop any new task dispatches. * Do NOT call taskq_wait() from a task: it will cause deadlock. * * void taskq_suspend(tq) * * Suspend all task execution. Tasks already scheduled for a dynamic task * queue will still be executed, but all new scheduled tasks will be * suspended until taskq_resume() is called. * * int taskq_suspended(tq) * * Returns 1 if taskq is suspended and 0 otherwise. It is intended to * ASSERT that the task queue is suspended. * * void taskq_resume(tq) * * Resume task queue execution. * * int taskq_member(tq, thread) * * Returns 1 if 'thread' belongs to taskq 'tq' and 0 otherwise. The * intended use is to ASSERT that a given function is called in taskq * context only. * * system_taskq * * Global system-wide dynamic task queue for common uses. It may be used by * any subsystem that needs to schedule tasks and does not need to manage * its own task queues. It is initialized quite early during system boot. * * IMPLEMENTATION ============================================================== * * This is schematic representation of the task queue structures. * * taskq: * +-------------+ * | tq_lock | +---< taskq_ent_free() * +-------------+ | * |... | | tqent: tqent: * +-------------+ | +------------+ +------------+ * | tq_freelist |-->| tqent_next |--> ... ->| tqent_next | * +-------------+ +------------+ +------------+ * |... | | ... | | ... | * +-------------+ +------------+ +------------+ * | tq_task | | * | | +-------------->taskq_ent_alloc() * +--------------------------------------------------------------------------+ * | | | tqent tqent | * | +---------------------+ +--> +------------+ +--> +------------+ | * | | ... | | | func, arg | | | func, arg | | * +>+---------------------+ <---|-+ +------------+ <---|-+ +------------+ | * | tq_taskq.tqent_next | ----+ | | tqent_next | --->+ | | tqent_next |--+ * +---------------------+ | +------------+ ^ | +------------+ * +-| tq_task.tqent_prev | +--| tqent_prev | | +--| tqent_prev | ^ * | +---------------------+ +------------+ | +------------+ | * | |... | | ... | | | ... | | * | +---------------------+ +------------+ | +------------+ | * | ^ | | * | | | | * +--------------------------------------+--------------+ TQ_APPEND() -+ * | | | * |... | taskq_thread()-----+ * +-------------+ * | tq_buckets |--+-------> [ NULL ] (for regular task queues) * +-------------+ | * | DYNAMIC TASK QUEUES: * | * +-> taskq_bucket[nCPU] taskq_bucket_dispatch() * +-------------------+ ^ * +--->| tqbucket_lock | | * | +-------------------+ +--------+ +--------+ * | | tqbucket_freelist |-->| tqent |-->...| tqent | ^ * | +-------------------+<--+--------+<--...+--------+ | * | | ... | | thread | | thread | | * | +-------------------+ +--------+ +--------+ | * | +-------------------+ | * taskq_dispatch()--+--->| tqbucket_lock | TQ_APPEND()------+ * TQ_HASH() | +-------------------+ +--------+ +--------+ * | | tqbucket_freelist |-->| tqent |-->...| tqent | * | +-------------------+<--+--------+<--...+--------+ * | | ... | | thread | | thread | * | +-------------------+ +--------+ +--------+ * +---> ... * * * Task queues use tq_task field to link new entry in the queue. The queue is a * circular doubly-linked list. Entries are put in the end of the list with * TQ_APPEND() and processed from the front of the list by taskq_thread() in * FIFO order. Task queue entries are cached in the free list managed by * taskq_ent_alloc() and taskq_ent_free() functions. * * All threads used by task queues mark t_taskq field of the thread to * point to the task queue. * * Taskq Thread Management ----------------------------------------------------- * * Taskq's non-dynamic threads are managed with several variables and flags: * * * tq_nthreads - The number of threads in taskq_thread() for the * taskq. * * * tq_active - The number of threads not waiting on a CV in * taskq_thread(); includes newly created threads * not yet counted in tq_nthreads. * * * tq_nthreads_target * - The number of threads desired for the taskq. * * * tq_flags & TASKQ_CHANGING * - Indicates that tq_nthreads != tq_nthreads_target. * * * tq_flags & TASKQ_THREAD_CREATED * - Indicates that a thread is being created in the taskq. * * During creation, tq_nthreads and tq_active are set to 0, and * tq_nthreads_target is set to the number of threads desired. The * TASKQ_CHANGING flag is set, and taskq_create_thread() is called to * create the first thread. taskq_create_thread() increments tq_active, * sets TASKQ_THREAD_CREATED, and creates the new thread. * * Each thread starts in taskq_thread(), clears the TASKQ_THREAD_CREATED * flag, and increments tq_nthreads. It stores the new value of * tq_nthreads as its "thread_id", and stores its thread pointer in the * tq_threadlist at the (thread_id - 1). We keep the thread_id space * densely packed by requiring that only the largest thread_id can exit during * normal adjustment. The exception is during the destruction of the * taskq; once tq_nthreads_target is set to zero, no new threads will be created * for the taskq queue, so every thread can exit without any ordering being * necessary. * * Threads will only process work if their thread id is <= tq_nthreads_target. * * When TASKQ_CHANGING is set, threads will check the current thread target * whenever they wake up, and do whatever they can to apply its effects. * * TASKQ_THREAD_CPU_PCT -------------------------------------------------------- * * When a taskq is created with TASKQ_THREAD_CPU_PCT, we store their requested * percentage in tq_threads_ncpus_pct, start them off with the correct thread * target, and add them to the taskq_cpupct_list for later adjustment. * * We register taskq_cpu_setup() to be called whenever a CPU changes state. It * walks the list of TASKQ_THREAD_CPU_PCT taskqs, adjusts their nthread_target * if need be, and wakes up all of the threads to process the change. * * Dynamic Task Queues Implementation ------------------------------------------ * * For a dynamic task queues there is a 1-to-1 mapping between a thread and * taskq_ent_structure. Each entry is serviced by its own thread and each thread * is controlled by a single entry. * * Entries are distributed over a set of buckets. To avoid using modulo * arithmetics the number of buckets is 2^n and is determined as the nearest * power of two roundown of the number of CPUs in the system. Tunable * variable 'taskq_maxbuckets' limits the maximum number of buckets. Each entry * is attached to a bucket for its lifetime and can't migrate to other buckets. * * Entries that have scheduled tasks are not placed in any list. The dispatch * function sets their "func" and "arg" fields and signals the corresponding * thread to execute the task. Once the thread executes the task it clears the * "func" field and places an entry on the bucket cache of free entries pointed * by "tqbucket_freelist" field. ALL entries on the free list should have "func" * field equal to NULL. The free list is a circular doubly-linked list identical * in structure to the tq_task list above, but entries are taken from it in LIFO * order - the last freed entry is the first to be allocated. The * taskq_bucket_dispatch() function gets the most recently used entry from the * free list, sets its "func" and "arg" fields and signals a worker thread. * * After executing each task a per-entry thread taskq_d_thread() places its * entry on the bucket free list and goes to a timed sleep. If it wakes up * without getting new task it removes the entry from the free list and destroys * itself. The thread sleep time is controlled by a tunable variable * `taskq_thread_timeout'. * * There are various statistics kept in the bucket which allows for later * analysis of taskq usage patterns. Also, a global copy of taskq creation and * death statistics is kept in the global taskq data structure. Since thread * creation and death happen rarely, updating such global data does not present * a performance problem. * * NOTE: Threads are not bound to any CPU and there is absolutely no association * between the bucket and actual thread CPU, so buckets are used only to * split resources and reduce resource contention. Having threads attached * to the CPU denoted by a bucket may reduce number of times the job * switches between CPUs. * * Current algorithm creates a thread whenever a bucket has no free * entries. It would be nice to know how many threads are in the running * state and don't create threads if all CPUs are busy with existing * tasks, but it is unclear how such strategy can be implemented. * * Currently buckets are created statically as an array attached to task * queue. On some system with nCPUs < max_ncpus it may waste system * memory. One solution may be allocation of buckets when they are first * touched, but it is not clear how useful it is. * * SUSPEND/RESUME implementation ----------------------------------------------- * * Before executing a task taskq_thread() (executing non-dynamic task * queues) obtains taskq's thread lock as a reader. The taskq_suspend() * function gets the same lock as a writer blocking all non-dynamic task * execution. The taskq_resume() function releases the lock allowing * taskq_thread to continue execution. * * For dynamic task queues, each bucket is marked as TQBUCKET_SUSPEND by * taskq_suspend() function. After that taskq_bucket_dispatch() always * fails, so that taskq_dispatch() will either enqueue tasks for a * suspended backing queue or fail if TQ_NOQUEUE is specified in dispatch * flags. * * NOTE: taskq_suspend() does not immediately block any tasks already * scheduled for dynamic task queues. It only suspends new tasks * scheduled after taskq_suspend() was called. * * taskq_member() function works by comparing a thread t_taskq pointer with * the passed thread pointer. * * LOCKS and LOCK Hierarchy ---------------------------------------------------- * * There are three locks used in task queues: * * 1) The taskq_t's tq_lock, protecting global task queue state. * * 2) Each per-CPU bucket has a lock for bucket management. * * 3) The global taskq_cpupct_lock, which protects the list of * TASKQ_THREADS_CPU_PCT taskqs. * * If both (1) and (2) are needed, tq_lock should be taken *after* the bucket * lock. * * If both (1) and (3) are needed, tq_lock should be taken *after* * taskq_cpupct_lock. * * DEBUG FACILITIES ------------------------------------------------------------ * * For DEBUG kernels it is possible to induce random failures to * taskq_dispatch() function when it is given TQ_NOSLEEP argument. The value of * taskq_dmtbf and taskq_smtbf tunables control the mean time between induced * failures for dynamic and static task queues respectively. * * Setting TASKQ_STATISTIC to 0 will disable per-bucket statistics. * * TUNABLES -------------------------------------------------------------------- * * system_taskq_size - Size of the global system_taskq. * This value is multiplied by nCPUs to determine * actual size. * Default value: 64 * * taskq_minimum_nthreads_max * - Minimum size of the thread list for a taskq. * Useful for testing different thread pool * sizes by overwriting tq_nthreads_target. * * taskq_thread_timeout - Maximum idle time for taskq_d_thread() * Default value: 5 minutes * * taskq_maxbuckets - Maximum number of buckets in any task queue * Default value: 128 * * taskq_search_depth - Maximum # of buckets searched for a free entry * Default value: 4 * * taskq_dmtbf - Mean time between induced dispatch failures * for dynamic task queues. * Default value: UINT_MAX (no induced failures) * * taskq_smtbf - Mean time between induced dispatch failures * for static task queues. * Default value: UINT_MAX (no induced failures) * * CONDITIONAL compilation ----------------------------------------------------- * * TASKQ_STATISTIC - If set will enable bucket statistic (default). * */ #include #include #include #include #include #include #include #include #include #include /* For throttlefree */ #include #include #include #include static kmem_cache_t *taskq_ent_cache, *taskq_cache; /* * Pseudo instance numbers for taskqs without explicitly provided instance. */ static vmem_t *taskq_id_arena; /* Global system task queue for common use */ taskq_t *system_taskq; /* * Maximum number of entries in global system taskq is * system_taskq_size * max_ncpus */ #define SYSTEM_TASKQ_SIZE 64 int system_taskq_size = SYSTEM_TASKQ_SIZE; /* * Minimum size for tq_nthreads_max; useful for those who want to play around * with increasing a taskq's tq_nthreads_target. */ int taskq_minimum_nthreads_max = 1; /* Maximum percentage allowed for TASKQ_THREADS_CPU_PCT */ #define TASKQ_CPUPCT_MAX_PERCENT 1000 int taskq_cpupct_max_percent = TASKQ_CPUPCT_MAX_PERCENT; /* * Dynamic task queue threads that don't get any work within * taskq_thread_timeout destroy themselves */ #define TASKQ_THREAD_TIMEOUT (60 * 5) int taskq_thread_timeout = TASKQ_THREAD_TIMEOUT; #define TASKQ_MAXBUCKETS 128 int taskq_maxbuckets = TASKQ_MAXBUCKETS; /* * When a bucket has no available entries another buckets are tried. * taskq_search_depth parameter limits the amount of buckets that we search * before failing. This is mostly useful in systems with many CPUs where we may * spend too much time scanning busy buckets. */ #define TASKQ_SEARCH_DEPTH 4 int taskq_search_depth = TASKQ_SEARCH_DEPTH; /* * Hashing function: mix various bits of x. May be pretty much anything. */ #define TQ_HASH(x) ((x) ^ ((x) >> 11) ^ ((x) >> 17) ^ ((x) ^ 27)) /* * We do not create any new threads when the system is low on memory and start * throttling memory allocations. The following macro tries to estimate such * condition. */ #define ENOUGH_MEMORY() (freemem > throttlefree) /* * Static functions. */ static taskq_t *taskq_create_common(const char *, int, int, pri_t, int, int, uint_t); static void taskq_thread(void *); static void taskq_d_thread(taskq_ent_t *); static void taskq_bucket_extend(void *); static int taskq_constructor(void *, void *, int); static void taskq_destructor(void *, void *); static int taskq_ent_constructor(void *, void *, int); static void taskq_ent_destructor(void *, void *); static taskq_ent_t *taskq_ent_alloc(taskq_t *, int); static void taskq_ent_free(taskq_t *, taskq_ent_t *); static taskq_ent_t *taskq_bucket_dispatch(taskq_bucket_t *, task_func_t, void *); /* * Task queues kstats. */ struct taskq_kstat { kstat_named_t tq_tasks; kstat_named_t tq_executed; kstat_named_t tq_maxtasks; kstat_named_t tq_totaltime; kstat_named_t tq_nalloc; kstat_named_t tq_nactive; kstat_named_t tq_pri; kstat_named_t tq_nthreads; } taskq_kstat = { { "tasks", KSTAT_DATA_UINT64 }, { "executed", KSTAT_DATA_UINT64 }, { "maxtasks", KSTAT_DATA_UINT64 }, { "totaltime", KSTAT_DATA_UINT64 }, { "nactive", KSTAT_DATA_UINT64 }, { "nalloc", KSTAT_DATA_UINT64 }, { "priority", KSTAT_DATA_UINT64 }, { "threads", KSTAT_DATA_UINT64 }, }; struct taskq_d_kstat { kstat_named_t tqd_pri; kstat_named_t tqd_btasks; kstat_named_t tqd_bexecuted; kstat_named_t tqd_bmaxtasks; kstat_named_t tqd_bnalloc; kstat_named_t tqd_bnactive; kstat_named_t tqd_btotaltime; kstat_named_t tqd_hits; kstat_named_t tqd_misses; kstat_named_t tqd_overflows; kstat_named_t tqd_tcreates; kstat_named_t tqd_tdeaths; kstat_named_t tqd_maxthreads; kstat_named_t tqd_nomem; kstat_named_t tqd_disptcreates; kstat_named_t tqd_totaltime; kstat_named_t tqd_nalloc; kstat_named_t tqd_nfree; } taskq_d_kstat = { { "priority", KSTAT_DATA_UINT64 }, { "btasks", KSTAT_DATA_UINT64 }, { "bexecuted", KSTAT_DATA_UINT64 }, { "bmaxtasks", KSTAT_DATA_UINT64 }, { "bnalloc", KSTAT_DATA_UINT64 }, { "bnactive", KSTAT_DATA_UINT64 }, { "btotaltime", KSTAT_DATA_UINT64 }, { "hits", KSTAT_DATA_UINT64 }, { "misses", KSTAT_DATA_UINT64 }, { "overflows", KSTAT_DATA_UINT64 }, { "tcreates", KSTAT_DATA_UINT64 }, { "tdeaths", KSTAT_DATA_UINT64 }, { "maxthreads", KSTAT_DATA_UINT64 }, { "nomem", KSTAT_DATA_UINT64 }, { "disptcreates", KSTAT_DATA_UINT64 }, { "totaltime", KSTAT_DATA_UINT64 }, { "nalloc", KSTAT_DATA_UINT64 }, { "nfree", KSTAT_DATA_UINT64 }, }; static kmutex_t taskq_kstat_lock; static kmutex_t taskq_d_kstat_lock; static int taskq_kstat_update(kstat_t *, int); static int taskq_d_kstat_update(kstat_t *, int); /* * State for THREAD_CPU_PCT management */ typedef struct taskq_cpupct_ent { list_node_t tp_link; taskq_t *tp_taskq; } taskq_cpupct_ent_t; static kmutex_t taskq_cpupct_lock; static list_t taskq_cpupct_list; static int taskq_cpupct_ncpus_online; /* * Collect per-bucket statistic when TASKQ_STATISTIC is defined. */ #define TASKQ_STATISTIC 1 #if TASKQ_STATISTIC #define TQ_STAT(b, x) b->tqbucket_stat.x++ #else #define TQ_STAT(b, x) #endif /* * Random fault injection. */ uint_t taskq_random; uint_t taskq_dmtbf = UINT_MAX; /* mean time between injected failures */ uint_t taskq_smtbf = UINT_MAX; /* mean time between injected failures */ /* * TQ_NOSLEEP dispatches on dynamic task queues are always allowed to fail. * * TQ_NOSLEEP dispatches on static task queues can't arbitrarily fail because * they could prepopulate the cache and make sure that they do not use more * then minalloc entries. So, fault injection in this case insures that * either TASKQ_PREPOPULATE is not set or there are more entries allocated * than is specified by minalloc. TQ_NOALLOC dispatches are always allowed * to fail, but for simplicity we treat them identically to TQ_NOSLEEP * dispatches. */ #ifdef DEBUG #define TASKQ_D_RANDOM_DISPATCH_FAILURE(tq, flag) \ taskq_random = (taskq_random * 2416 + 374441) % 1771875;\ if ((flag & TQ_NOSLEEP) && \ taskq_random < 1771875 / taskq_dmtbf) { \ return (NULL); \ } #define TASKQ_S_RANDOM_DISPATCH_FAILURE(tq, flag) \ taskq_random = (taskq_random * 2416 + 374441) % 1771875;\ if ((flag & (TQ_NOSLEEP | TQ_NOALLOC)) && \ (!(tq->tq_flags & TASKQ_PREPOPULATE) || \ (tq->tq_nalloc > tq->tq_minalloc)) && \ (taskq_random < (1771875 / taskq_smtbf))) { \ mutex_exit(&tq->tq_lock); \ return (NULL); \ } #else #define TASKQ_S_RANDOM_DISPATCH_FAILURE(tq, flag) #define TASKQ_D_RANDOM_DISPATCH_FAILURE(tq, flag) #endif #define IS_EMPTY(l) (((l).tqent_prev == (l).tqent_next) && \ ((l).tqent_prev == &(l))) /* * Append `tqe' in the end of the doubly-linked list denoted by l. */ #define TQ_APPEND(l, tqe) { \ tqe->tqent_next = &l; \ tqe->tqent_prev = l.tqent_prev; \ tqe->tqent_next->tqent_prev = tqe; \ tqe->tqent_prev->tqent_next = tqe; \ } /* * Schedule a task specified by func and arg into the task queue entry tqe. */ #define TQ_ENQUEUE(tq, tqe, func, arg) { \ ASSERT(MUTEX_HELD(&tq->tq_lock)); \ TQ_APPEND(tq->tq_task, tqe); \ tqe->tqent_func = (func); \ tqe->tqent_arg = (arg); \ tq->tq_tasks++; \ if (tq->tq_tasks - tq->tq_executed > tq->tq_maxtasks) \ tq->tq_maxtasks = tq->tq_tasks - tq->tq_executed; \ cv_signal(&tq->tq_dispatch_cv); \ DTRACE_PROBE2(taskq__enqueue, taskq_t *, tq, taskq_ent_t *, tqe); \ } /* * Do-nothing task which may be used to prepopulate thread caches. */ /*ARGSUSED*/ void nulltask(void *unused) { } /*ARGSUSED*/ static int taskq_constructor(void *buf, void *cdrarg, int kmflags) { taskq_t *tq = buf; bzero(tq, sizeof (taskq_t)); mutex_init(&tq->tq_lock, NULL, MUTEX_DEFAULT, NULL); rw_init(&tq->tq_threadlock, NULL, RW_DEFAULT, NULL); cv_init(&tq->tq_dispatch_cv, NULL, CV_DEFAULT, NULL); cv_init(&tq->tq_exit_cv, NULL, CV_DEFAULT, NULL); cv_init(&tq->tq_wait_cv, NULL, CV_DEFAULT, NULL); tq->tq_task.tqent_next = &tq->tq_task; tq->tq_task.tqent_prev = &tq->tq_task; return (0); } /*ARGSUSED*/ static void taskq_destructor(void *buf, void *cdrarg) { taskq_t *tq = buf; ASSERT(tq->tq_nthreads == 0); ASSERT(tq->tq_buckets == NULL); ASSERT(tq->tq_tcreates == 0); ASSERT(tq->tq_tdeaths == 0); mutex_destroy(&tq->tq_lock); rw_destroy(&tq->tq_threadlock); cv_destroy(&tq->tq_dispatch_cv); cv_destroy(&tq->tq_exit_cv); cv_destroy(&tq->tq_wait_cv); } /*ARGSUSED*/ static int taskq_ent_constructor(void *buf, void *cdrarg, int kmflags) { taskq_ent_t *tqe = buf; tqe->tqent_thread = NULL; cv_init(&tqe->tqent_cv, NULL, CV_DEFAULT, NULL); return (0); } /*ARGSUSED*/ static void taskq_ent_destructor(void *buf, void *cdrarg) { taskq_ent_t *tqe = buf; ASSERT(tqe->tqent_thread == NULL); cv_destroy(&tqe->tqent_cv); } void taskq_init(void) { taskq_ent_cache = kmem_cache_create("taskq_ent_cache", sizeof (taskq_ent_t), 0, taskq_ent_constructor, taskq_ent_destructor, NULL, NULL, NULL, 0); taskq_cache = kmem_cache_create("taskq_cache", sizeof (taskq_t), 0, taskq_constructor, taskq_destructor, NULL, NULL, NULL, 0); taskq_id_arena = vmem_create("taskq_id_arena", (void *)1, INT32_MAX, 1, NULL, NULL, NULL, 0, VM_SLEEP | VMC_IDENTIFIER); list_create(&taskq_cpupct_list, sizeof (taskq_cpupct_ent_t), offsetof(taskq_cpupct_ent_t, tp_link)); } /*ARGSUSED*/ static int taskq_cpu_setup(cpu_setup_t what, int id, void *arg) { taskq_cpupct_ent_t *tpp; int cpus_online = ncpus_online; /* offlines are called *before* the cpu is offlined. */ if (what == CPU_OFF) cpus_online--; if (cpus_online < 1) cpus_online = 1; mutex_enter(&taskq_cpupct_lock); if (cpus_online == taskq_cpupct_ncpus_online) { mutex_exit(&taskq_cpupct_lock); return (0); } for (tpp = list_head(&taskq_cpupct_list); tpp != NULL; tpp = list_next(&taskq_cpupct_list, tpp)) { taskq_t *tq = tpp->tp_taskq; int newtarget; mutex_enter(&tq->tq_lock); newtarget = TASKQ_THREADS_PCT(cpus_online, tq->tq_threads_ncpus_pct); ASSERT3S(newtarget, <=, tq->tq_nthreads_max); if (newtarget != tq->tq_nthreads_target) { /* The taskq must not be exiting */ ASSERT3S(tq->tq_nthreads_target, !=, 0); tq->tq_flags |= TASKQ_CHANGING; tq->tq_nthreads_target = newtarget; cv_broadcast(&tq->tq_dispatch_cv); cv_broadcast(&tq->tq_exit_cv); } mutex_exit(&tq->tq_lock); } taskq_cpupct_ncpus_online = cpus_online; mutex_exit(&taskq_cpupct_lock); return (0); } void taskq_mp_init(void) { mutex_enter(&cpu_lock); register_cpu_setup_func(taskq_cpu_setup, NULL); (void) taskq_cpu_setup(CPU_ON, 0, NULL); mutex_exit(&cpu_lock); } /* * Create global system dynamic task queue. */ void system_taskq_init(void) { system_taskq = taskq_create_common("system_taskq", 0, system_taskq_size * max_ncpus, minclsyspri, 4, 512, TASKQ_DYNAMIC | TASKQ_PREPOPULATE); } /* * taskq_ent_alloc() * * Allocates a new taskq_ent_t structure either from the free list or from the * cache. Returns NULL if it can't be allocated. * * Assumes: tq->tq_lock is held. */ static taskq_ent_t * taskq_ent_alloc(taskq_t *tq, int flags) { int kmflags = (flags & TQ_NOSLEEP) ? KM_NOSLEEP : KM_SLEEP; taskq_ent_t *tqe; ASSERT(MUTEX_HELD(&tq->tq_lock)); /* * TQ_NOALLOC allocations are allowed to use the freelist, even if * we are below tq_minalloc. */ if ((tqe = tq->tq_freelist) != NULL && ((flags & TQ_NOALLOC) || tq->tq_nalloc >= tq->tq_minalloc)) { tq->tq_freelist = tqe->tqent_next; } else { if (flags & TQ_NOALLOC) return (NULL); mutex_exit(&tq->tq_lock); if (tq->tq_nalloc >= tq->tq_maxalloc) { if (kmflags & KM_NOSLEEP) { mutex_enter(&tq->tq_lock); return (NULL); } /* * We don't want to exceed tq_maxalloc, but we can't * wait for other tasks to complete (and thus free up * task structures) without risking deadlock with * the caller. So, we just delay for one second * to throttle the allocation rate. */ delay(hz); } tqe = kmem_cache_alloc(taskq_ent_cache, kmflags); mutex_enter(&tq->tq_lock); if (tqe != NULL) tq->tq_nalloc++; } return (tqe); } /* * taskq_ent_free() * * Free taskq_ent_t structure by either putting it on the free list or freeing * it to the cache. * * Assumes: tq->tq_lock is held. */ static void taskq_ent_free(taskq_t *tq, taskq_ent_t *tqe) { ASSERT(MUTEX_HELD(&tq->tq_lock)); if (tq->tq_nalloc <= tq->tq_minalloc) { tqe->tqent_next = tq->tq_freelist; tq->tq_freelist = tqe; } else { tq->tq_nalloc--; mutex_exit(&tq->tq_lock); kmem_cache_free(taskq_ent_cache, tqe); mutex_enter(&tq->tq_lock); } } /* * Dispatch a task "func(arg)" to a free entry of bucket b. * * Assumes: no bucket locks is held. * * Returns: a pointer to an entry if dispatch was successful. * NULL if there are no free entries or if the bucket is suspended. */ static taskq_ent_t * taskq_bucket_dispatch(taskq_bucket_t *b, task_func_t func, void *arg) { taskq_ent_t *tqe; ASSERT(MUTEX_NOT_HELD(&b->tqbucket_lock)); ASSERT(func != NULL); mutex_enter(&b->tqbucket_lock); ASSERT(b->tqbucket_nfree != 0 || IS_EMPTY(b->tqbucket_freelist)); ASSERT(b->tqbucket_nfree == 0 || !IS_EMPTY(b->tqbucket_freelist)); /* * Get en entry from the freelist if there is one. * Schedule task into the entry. */ if ((b->tqbucket_nfree != 0) && !(b->tqbucket_flags & TQBUCKET_SUSPEND)) { tqe = b->tqbucket_freelist.tqent_prev; ASSERT(tqe != &b->tqbucket_freelist); ASSERT(tqe->tqent_thread != NULL); tqe->tqent_prev->tqent_next = tqe->tqent_next; tqe->tqent_next->tqent_prev = tqe->tqent_prev; b->tqbucket_nalloc++; b->tqbucket_nfree--; tqe->tqent_func = func; tqe->tqent_arg = arg; TQ_STAT(b, tqs_hits); cv_signal(&tqe->tqent_cv); DTRACE_PROBE2(taskq__d__enqueue, taskq_bucket_t *, b, taskq_ent_t *, tqe); } else { tqe = NULL; TQ_STAT(b, tqs_misses); } mutex_exit(&b->tqbucket_lock); return (tqe); } /* * Dispatch a task. * * Assumes: func != NULL * * Returns: NULL if dispatch failed. * non-NULL if task dispatched successfully. * Actual return value is the pointer to taskq entry that was used to * dispatch a task. This is useful for debugging. */ /* ARGSUSED */ taskqid_t taskq_dispatch(taskq_t *tq, task_func_t func, void *arg, uint_t flags) { taskq_bucket_t *bucket = NULL; /* Which bucket needs extension */ taskq_ent_t *tqe = NULL; taskq_ent_t *tqe1; uint_t bsize; ASSERT(tq != NULL); ASSERT(func != NULL); if (!(tq->tq_flags & TASKQ_DYNAMIC)) { /* * TQ_NOQUEUE flag can't be used with non-dynamic task queues. */ ASSERT(! (flags & TQ_NOQUEUE)); /* * Enqueue the task to the underlying queue. */ mutex_enter(&tq->tq_lock); TASKQ_S_RANDOM_DISPATCH_FAILURE(tq, flags); if ((tqe = taskq_ent_alloc(tq, flags)) == NULL) { mutex_exit(&tq->tq_lock); return (NULL); } TQ_ENQUEUE(tq, tqe, func, arg); mutex_exit(&tq->tq_lock); return ((taskqid_t)tqe); } /* * Dynamic taskq dispatching. */ ASSERT(!(flags & TQ_NOALLOC)); TASKQ_D_RANDOM_DISPATCH_FAILURE(tq, flags); bsize = tq->tq_nbuckets; if (bsize == 1) { /* * In a single-CPU case there is only one bucket, so get * entry directly from there. */ if ((tqe = taskq_bucket_dispatch(tq->tq_buckets, func, arg)) != NULL) return ((taskqid_t)tqe); /* Fastpath */ bucket = tq->tq_buckets; } else { int loopcount; taskq_bucket_t *b; uintptr_t h = ((uintptr_t)CPU + (uintptr_t)arg) >> 3; h = TQ_HASH(h); /* * The 'bucket' points to the original bucket that we hit. If we * can't allocate from it, we search other buckets, but only * extend this one. */ b = &tq->tq_buckets[h & (bsize - 1)]; ASSERT(b->tqbucket_taskq == tq); /* Sanity check */ /* * Do a quick check before grabbing the lock. If the bucket does * not have free entries now, chances are very small that it * will after we take the lock, so we just skip it. */ if (b->tqbucket_nfree != 0) { if ((tqe = taskq_bucket_dispatch(b, func, arg)) != NULL) return ((taskqid_t)tqe); /* Fastpath */ } else { TQ_STAT(b, tqs_misses); } bucket = b; loopcount = MIN(taskq_search_depth, bsize); /* * If bucket dispatch failed, search loopcount number of buckets * before we give up and fail. */ do { b = &tq->tq_buckets[++h & (bsize - 1)]; ASSERT(b->tqbucket_taskq == tq); /* Sanity check */ loopcount--; if (b->tqbucket_nfree != 0) { tqe = taskq_bucket_dispatch(b, func, arg); } else { TQ_STAT(b, tqs_misses); } } while ((tqe == NULL) && (loopcount > 0)); } /* * At this point we either scheduled a task and (tqe != NULL) or failed * (tqe == NULL). Try to recover from fails. */ /* * For KM_SLEEP dispatches, try to extend the bucket and retry dispatch. */ if ((tqe == NULL) && !(flags & TQ_NOSLEEP)) { /* * taskq_bucket_extend() may fail to do anything, but this is * fine - we deal with it later. If the bucket was successfully * extended, there is a good chance that taskq_bucket_dispatch() * will get this new entry, unless someone is racing with us and * stealing the new entry from under our nose. * taskq_bucket_extend() may sleep. */ taskq_bucket_extend(bucket); TQ_STAT(bucket, tqs_disptcreates); if ((tqe = taskq_bucket_dispatch(bucket, func, arg)) != NULL) return ((taskqid_t)tqe); } ASSERT(bucket != NULL); /* * Since there are not enough free entries in the bucket, extend it * in the background using backing queue. */ mutex_enter(&tq->tq_lock); if ((tqe1 = taskq_ent_alloc(tq, TQ_NOSLEEP)) != NULL) { TQ_ENQUEUE(tq, tqe1, taskq_bucket_extend, bucket); } else { TQ_STAT(bucket, tqs_nomem); } /* * Dispatch failed and we can't find an entry to schedule a task. * Revert to the backing queue unless TQ_NOQUEUE was asked. */ if ((tqe == NULL) && !(flags & TQ_NOQUEUE)) { if ((tqe = taskq_ent_alloc(tq, flags)) != NULL) { TQ_ENQUEUE(tq, tqe, func, arg); } else { TQ_STAT(bucket, tqs_nomem); } } mutex_exit(&tq->tq_lock); return ((taskqid_t)tqe); } /* * Wait for all pending tasks to complete. * Calling taskq_wait from a task will cause deadlock. */ void taskq_wait(taskq_t *tq) { ASSERT(tq != curthread->t_taskq); mutex_enter(&tq->tq_lock); while (tq->tq_task.tqent_next != &tq->tq_task || tq->tq_active != 0) cv_wait(&tq->tq_wait_cv, &tq->tq_lock); mutex_exit(&tq->tq_lock); if (tq->tq_flags & TASKQ_DYNAMIC) { taskq_bucket_t *b = tq->tq_buckets; int bid = 0; for (; (b != NULL) && (bid < tq->tq_nbuckets); b++, bid++) { mutex_enter(&b->tqbucket_lock); while (b->tqbucket_nalloc > 0) cv_wait(&b->tqbucket_cv, &b->tqbucket_lock); mutex_exit(&b->tqbucket_lock); } } } /* * Suspend execution of tasks. * * Tasks in the queue part will be suspended immediately upon return from this * function. Pending tasks in the dynamic part will continue to execute, but all * new tasks will be suspended. */ void taskq_suspend(taskq_t *tq) { rw_enter(&tq->tq_threadlock, RW_WRITER); if (tq->tq_flags & TASKQ_DYNAMIC) { taskq_bucket_t *b = tq->tq_buckets; int bid = 0; for (; (b != NULL) && (bid < tq->tq_nbuckets); b++, bid++) { mutex_enter(&b->tqbucket_lock); b->tqbucket_flags |= TQBUCKET_SUSPEND; mutex_exit(&b->tqbucket_lock); } } /* * Mark task queue as being suspended. Needed for taskq_suspended(). */ mutex_enter(&tq->tq_lock); ASSERT(!(tq->tq_flags & TASKQ_SUSPENDED)); tq->tq_flags |= TASKQ_SUSPENDED; mutex_exit(&tq->tq_lock); } /* * returns: 1 if tq is suspended, 0 otherwise. */ int taskq_suspended(taskq_t *tq) { return ((tq->tq_flags & TASKQ_SUSPENDED) != 0); } /* * Resume taskq execution. */ void taskq_resume(taskq_t *tq) { ASSERT(RW_WRITE_HELD(&tq->tq_threadlock)); if (tq->tq_flags & TASKQ_DYNAMIC) { taskq_bucket_t *b = tq->tq_buckets; int bid = 0; for (; (b != NULL) && (bid < tq->tq_nbuckets); b++, bid++) { mutex_enter(&b->tqbucket_lock); b->tqbucket_flags &= ~TQBUCKET_SUSPEND; mutex_exit(&b->tqbucket_lock); } } mutex_enter(&tq->tq_lock); ASSERT(tq->tq_flags & TASKQ_SUSPENDED); tq->tq_flags &= ~TASKQ_SUSPENDED; mutex_exit(&tq->tq_lock); rw_exit(&tq->tq_threadlock); } int taskq_member(taskq_t *tq, kthread_t *thread) { return (thread->t_taskq == tq); } static void taskq_thread_create(taskq_t *tq) { kthread_t *t; ASSERT(MUTEX_HELD(&tq->tq_lock)); ASSERT(!(tq->tq_flags & TASKQ_THREAD_CREATED)); tq->tq_flags |= TASKQ_THREAD_CREATED; tq->tq_active++; t = thread_create(NULL, 0, taskq_thread, tq, 0, &p0, TS_RUN, tq->tq_pri); t->t_taskq = tq; } /* * Common "sleep taskq thread" function, which handles CPR stuff, as well * as giving a nice common point for debuggers to find inactive threads. */ static clock_t taskq_thread_wait(taskq_t *tq, kmutex_t *mx, kcondvar_t *cv, callb_cpr_t *cprinfo, clock_t timeout) { clock_t ret = 0; if (!(tq->tq_flags & TASKQ_CPR_SAFE)) { CALLB_CPR_SAFE_BEGIN(cprinfo); } if (timeout < 0) cv_wait(cv, mx); else ret = cv_timedwait(cv, mx, lbolt + timeout); if (!(tq->tq_flags & TASKQ_CPR_SAFE)) { CALLB_CPR_SAFE_END(cprinfo, mx); } return (ret); } /* * Worker thread for processing task queue. */ static void taskq_thread(void *arg) { int thread_id; taskq_t *tq = arg; taskq_ent_t *tqe; callb_cpr_t cprinfo; hrtime_t start, end; if (tq->tq_flags & TASKQ_CPR_SAFE) { CALLB_CPR_INIT_SAFE(curthread, tq->tq_name); } else { CALLB_CPR_INIT(&cprinfo, &tq->tq_lock, callb_generic_cpr, tq->tq_name); } mutex_enter(&tq->tq_lock); thread_id = ++tq->tq_nthreads; ASSERT(tq->tq_flags & TASKQ_THREAD_CREATED); tq->tq_flags &= ~TASKQ_THREAD_CREATED; VERIFY3S(thread_id, <=, tq->tq_nthreads_max); if (tq->tq_nthreads_max == 1) tq->tq_thread = curthread; else tq->tq_threadlist[thread_id - 1] = curthread; for (;;) { if (tq->tq_flags & TASKQ_CHANGING) { /* we're done; clear the CHANGING flag */ if (tq->tq_nthreads == tq->tq_nthreads_target) { tq->tq_flags &= ~TASKQ_CHANGING; continue; } /* We're low on threads and none have been created */ if (tq->tq_nthreads < tq->tq_nthreads_target && !(tq->tq_flags & TASKQ_THREAD_CREATED)) { taskq_thread_create(tq); continue; } /* We're no longer needed */ if (thread_id > tq->tq_nthreads_target) { /* * To preserve the one-to-one mapping between * thread_id and thread, we must exit from * highest thread ID to least. * * However, if everyone is exiting, the order * doesn't matter, so just exit immediately. * (this is safe, since you must wait for * nthreads to reach 0 after setting * tq_nthreads_target to 0) */ if (thread_id == tq->tq_nthreads || tq->tq_nthreads_target == 0) break; /* Wait for higher thread_ids to exit */ (void) taskq_thread_wait(tq, &tq->tq_lock, &tq->tq_exit_cv, &cprinfo, -1); continue; } } if ((tqe = tq->tq_task.tqent_next) == &tq->tq_task) { if (--tq->tq_active == 0) cv_broadcast(&tq->tq_wait_cv); (void) taskq_thread_wait(tq, &tq->tq_lock, &tq->tq_dispatch_cv, &cprinfo, -1); tq->tq_active++; continue; } tqe->tqent_prev->tqent_next = tqe->tqent_next; tqe->tqent_next->tqent_prev = tqe->tqent_prev; mutex_exit(&tq->tq_lock); rw_enter(&tq->tq_threadlock, RW_READER); start = gethrtime(); DTRACE_PROBE2(taskq__exec__start, taskq_t *, tq, taskq_ent_t *, tqe); tqe->tqent_func(tqe->tqent_arg); DTRACE_PROBE2(taskq__exec__end, taskq_t *, tq, taskq_ent_t *, tqe); end = gethrtime(); rw_exit(&tq->tq_threadlock); mutex_enter(&tq->tq_lock); tq->tq_totaltime += end - start; tq->tq_executed++; taskq_ent_free(tq, tqe); } if (tq->tq_nthreads_max == 1) tq->tq_thread = NULL; else tq->tq_threadlist[thread_id - 1] = NULL; ASSERT(tq->tq_nthreads > 0); if (--tq->tq_nthreads == 0) cv_broadcast(&tq->tq_wait_cv); /* let the other threads which need to exit know we're done */ cv_broadcast(&tq->tq_exit_cv); /* We're exiting, and therefore no longer active */ tq->tq_active--; ASSERT(!(tq->tq_flags & TASKQ_CPR_SAFE)); CALLB_CPR_EXIT(&cprinfo); thread_exit(); } /* * Worker per-entry thread for dynamic dispatches. */ static void taskq_d_thread(taskq_ent_t *tqe) { taskq_bucket_t *bucket = tqe->tqent_bucket; taskq_t *tq = bucket->tqbucket_taskq; kmutex_t *lock = &bucket->tqbucket_lock; kcondvar_t *cv = &tqe->tqent_cv; callb_cpr_t cprinfo; clock_t w; CALLB_CPR_INIT(&cprinfo, lock, callb_generic_cpr, tq->tq_name); mutex_enter(lock); for (;;) { /* * If a task is scheduled (func != NULL), execute it, otherwise * sleep, waiting for a job. */ if (tqe->tqent_func != NULL) { hrtime_t start; hrtime_t end; ASSERT(bucket->tqbucket_nalloc > 0); /* * It is possible to free the entry right away before * actually executing the task so that subsequent * dispatches may immediately reuse it. But this, * effectively, creates a two-length queue in the entry * and may lead to a deadlock if the execution of the * current task depends on the execution of the next * scheduled task. So, we keep the entry busy until the * task is processed. */ mutex_exit(lock); start = gethrtime(); DTRACE_PROBE3(taskq__d__exec__start, taskq_t *, tq, taskq_bucket_t *, bucket, taskq_ent_t *, tqe); tqe->tqent_func(tqe->tqent_arg); DTRACE_PROBE3(taskq__d__exec__end, taskq_t *, tq, taskq_bucket_t *, bucket, taskq_ent_t *, tqe); end = gethrtime(); mutex_enter(lock); bucket->tqbucket_totaltime += end - start; /* * Return the entry to the bucket free list. */ tqe->tqent_func = NULL; TQ_APPEND(bucket->tqbucket_freelist, tqe); bucket->tqbucket_nalloc--; bucket->tqbucket_nfree++; ASSERT(!IS_EMPTY(bucket->tqbucket_freelist)); /* * taskq_wait() waits for nalloc to drop to zero on * tqbucket_cv. */ cv_signal(&bucket->tqbucket_cv); } /* * At this point the entry must be in the bucket free list - * either because it was there initially or because it just * finished executing a task and put itself on the free list. */ ASSERT(bucket->tqbucket_nfree > 0); /* * Go to sleep unless we are closing. * If a thread is sleeping too long, it dies. */ if (! (bucket->tqbucket_flags & TQBUCKET_CLOSE)) { w = taskq_thread_wait(tq, lock, cv, &cprinfo, taskq_thread_timeout * hz); } /* * At this point we may be in two different states: * * (1) tqent_func is set which means that a new task is * dispatched and we need to execute it. * * (2) Thread is sleeping for too long or we are closing. In * both cases destroy the thread and the entry. */ /* If func is NULL we should be on the freelist. */ ASSERT((tqe->tqent_func != NULL) || (bucket->tqbucket_nfree > 0)); /* If func is non-NULL we should be allocated */ ASSERT((tqe->tqent_func == NULL) || (bucket->tqbucket_nalloc > 0)); /* Check freelist consistency */ ASSERT((bucket->tqbucket_nfree > 0) || IS_EMPTY(bucket->tqbucket_freelist)); ASSERT((bucket->tqbucket_nfree == 0) || !IS_EMPTY(bucket->tqbucket_freelist)); if ((tqe->tqent_func == NULL) && ((w == -1) || (bucket->tqbucket_flags & TQBUCKET_CLOSE))) { /* * This thread is sleeping for too long or we are * closing - time to die. * Thread creation/destruction happens rarely, * so grabbing the lock is not a big performance issue. * The bucket lock is dropped by CALLB_CPR_EXIT(). */ /* Remove the entry from the free list. */ tqe->tqent_prev->tqent_next = tqe->tqent_next; tqe->tqent_next->tqent_prev = tqe->tqent_prev; ASSERT(bucket->tqbucket_nfree > 0); bucket->tqbucket_nfree--; TQ_STAT(bucket, tqs_tdeaths); cv_signal(&bucket->tqbucket_cv); tqe->tqent_thread = NULL; mutex_enter(&tq->tq_lock); tq->tq_tdeaths++; mutex_exit(&tq->tq_lock); CALLB_CPR_EXIT(&cprinfo); kmem_cache_free(taskq_ent_cache, tqe); thread_exit(); } } } /* * Taskq creation. May sleep for memory. * Always use automatically generated instances to avoid kstat name space * collisions. */ taskq_t * taskq_create(const char *name, int nthreads, pri_t pri, int minalloc, int maxalloc, uint_t flags) { return taskq_create_common(name, 0, nthreads, pri, minalloc, maxalloc, flags | TASKQ_NOINSTANCE); } /* * Create an instance of task queue. It is legal to create task queues with the * same name and different instances. * * taskq_create_instance is used by ddi_taskq_create() where it gets the * instance from ddi_get_instance(). In some cases the instance is not * initialized and is set to -1. This case is handled as if no instance was * passed at all. */ taskq_t * taskq_create_instance(const char *name, int instance, int nthreads, pri_t pri, int minalloc, int maxalloc, uint_t flags) { ASSERT((instance >= 0) || (instance == -1)); if (instance < 0) { flags |= TASKQ_NOINSTANCE; } return (taskq_create_common(name, instance, nthreads, pri, minalloc, maxalloc, flags)); } static taskq_t * taskq_create_common(const char *name, int instance, int nthreads, pri_t pri, int minalloc, int maxalloc, uint_t flags) { taskq_t *tq = kmem_cache_alloc(taskq_cache, KM_SLEEP); uint_t ncpus = ((boot_max_ncpus == -1) ? max_ncpus : boot_max_ncpus); uint_t bsize; /* # of buckets - always power of 2 */ int max_nthreads; /* * TASKQ_DYNAMIC is incompatible with TASKQ_CPR_SAFE and * TASKQ_THREADS_CPU_PCT. */ ASSERT(!(flags & TASKQ_DYNAMIC) || !(flags & (TASKQ_CPR_SAFE | TASKQ_THREADS_CPU_PCT))); /* TASKQ_CPR_SAFE is incompatible with TASKQ_THREADS_CPU_PCT */ ASSERT(!(flags & TASKQ_CPR_SAFE) || !(flags & TASKQ_THREADS_CPU_PCT)); bsize = 1 << (highbit(ncpus) - 1); ASSERT(bsize >= 1); bsize = MIN(bsize, taskq_maxbuckets); if (flags & TASKQ_DYNAMIC) { ASSERT3S(nthreads, >=, 1); tq->tq_maxsize = nthreads; /* For dynamic task queues use just one backup thread */ nthreads = max_nthreads = 1; } else if (!(flags & TASKQ_THREADS_CPU_PCT)) { ASSERT3S(nthreads, >=, 1); max_nthreads = nthreads; } else { uint_t pct; ASSERT3S(nthreads, >=, 0); pct = nthreads; if (pct > taskq_cpupct_max_percent) pct = taskq_cpupct_max_percent; tq->tq_threads_ncpus_pct = pct; nthreads = TASKQ_THREADS_PCT(ncpus_online, pct); max_nthreads = TASKQ_THREADS_PCT(max_ncpus, pct); } if (max_nthreads < taskq_minimum_nthreads_max) max_nthreads = taskq_minimum_nthreads_max; /* * Make sure the name is 0-terminated, and conforms to the rules for * C indentifiers */ (void) strncpy(tq->tq_name, name, TASKQ_NAMELEN + 1); strident_canon(tq->tq_name, TASKQ_NAMELEN + 1); tq->tq_flags = flags | TASKQ_CHANGING; tq->tq_active = 0; tq->tq_instance = instance; tq->tq_nthreads_target = nthreads; tq->tq_nthreads_max = max_nthreads; tq->tq_minalloc = minalloc; tq->tq_maxalloc = maxalloc; tq->tq_nbuckets = bsize; tq->tq_pri = pri; if (max_nthreads > 1) tq->tq_threadlist = kmem_alloc( sizeof (kthread_t *) * max_nthreads, KM_SLEEP); /* Add the taskq to the list of CPU_PCT taskqs */ if (flags & TASKQ_THREADS_CPU_PCT) { taskq_cpupct_ent_t *tpp = kmem_zalloc(sizeof (*tpp), KM_SLEEP); list_link_init(&tpp->tp_link); tpp->tp_taskq = tq; mutex_enter(&taskq_cpupct_lock); list_insert_tail(&taskq_cpupct_list, tpp); /* reset our target, to avoid race conditions */ tq->tq_nthreads_target = TASKQ_THREADS_PCT(ncpus_online, tq->tq_threads_ncpus_pct); mutex_exit(&taskq_cpupct_lock); } mutex_enter(&tq->tq_lock); if (flags & TASKQ_PREPOPULATE) { while (minalloc-- > 0) taskq_ent_free(tq, taskq_ent_alloc(tq, TQ_SLEEP)); } /* create the first thread; if more are needed, it'll create them */ taskq_thread_create(tq); mutex_exit(&tq->tq_lock); if (flags & TASKQ_DYNAMIC) { taskq_bucket_t *bucket = kmem_zalloc(sizeof (taskq_bucket_t) * bsize, KM_SLEEP); int b_id; tq->tq_buckets = bucket; /* Initialize each bucket */ for (b_id = 0; b_id < bsize; b_id++, bucket++) { mutex_init(&bucket->tqbucket_lock, NULL, MUTEX_DEFAULT, NULL); cv_init(&bucket->tqbucket_cv, NULL, CV_DEFAULT, NULL); bucket->tqbucket_taskq = tq; bucket->tqbucket_freelist.tqent_next = bucket->tqbucket_freelist.tqent_prev = &bucket->tqbucket_freelist; if (flags & TASKQ_PREPOPULATE) taskq_bucket_extend(bucket); } } /* * Install kstats. * We have two cases: * 1) Instance is provided to taskq_create_instance(). In this case it * should be >= 0 and we use it. * * 2) Instance is not provided and is automatically generated */ if (flags & TASKQ_NOINSTANCE) { instance = tq->tq_instance = (int)(uintptr_t)vmem_alloc(taskq_id_arena, 1, VM_SLEEP); } if (flags & TASKQ_DYNAMIC) { if ((tq->tq_kstat = kstat_create("unix", instance, tq->tq_name, "taskq_d", KSTAT_TYPE_NAMED, sizeof (taskq_d_kstat) / sizeof (kstat_named_t), KSTAT_FLAG_VIRTUAL)) != NULL) { tq->tq_kstat->ks_lock = &taskq_d_kstat_lock; tq->tq_kstat->ks_data = &taskq_d_kstat; tq->tq_kstat->ks_update = taskq_d_kstat_update; tq->tq_kstat->ks_private = tq; kstat_install(tq->tq_kstat); } } else { if ((tq->tq_kstat = kstat_create("unix", instance, tq->tq_name, "taskq", KSTAT_TYPE_NAMED, sizeof (taskq_kstat) / sizeof (kstat_named_t), KSTAT_FLAG_VIRTUAL)) != NULL) { tq->tq_kstat->ks_lock = &taskq_kstat_lock; tq->tq_kstat->ks_data = &taskq_kstat; tq->tq_kstat->ks_update = taskq_kstat_update; tq->tq_kstat->ks_private = tq; kstat_install(tq->tq_kstat); } } return (tq); } /* * taskq_destroy(). * * Assumes: by the time taskq_destroy is called no one will use this task queue * in any way and no one will try to dispatch entries in it. */ void taskq_destroy(taskq_t *tq) { taskq_bucket_t *b = tq->tq_buckets; int bid = 0; ASSERT(! (tq->tq_flags & TASKQ_CPR_SAFE)); /* * Destroy kstats. */ if (tq->tq_kstat != NULL) { kstat_delete(tq->tq_kstat); tq->tq_kstat = NULL; } /* * Destroy instance if needed. */ if (tq->tq_flags & TASKQ_NOINSTANCE) { vmem_free(taskq_id_arena, (void *)(uintptr_t)(tq->tq_instance), 1); tq->tq_instance = 0; } /* * Unregister from the cpupct list. */ if (tq->tq_flags & TASKQ_THREADS_CPU_PCT) { taskq_cpupct_ent_t *tpp; mutex_enter(&taskq_cpupct_lock); for (tpp = list_head(&taskq_cpupct_list); tpp != NULL; tpp = list_next(&taskq_cpupct_list, tpp)) { if (tpp->tp_taskq == tq) break; } ASSERT3P(tpp, !=, NULL); list_remove(&taskq_cpupct_list, tpp); mutex_exit(&taskq_cpupct_lock); kmem_free(tpp, sizeof (*tpp)); } /* * Wait for any pending entries to complete. */ taskq_wait(tq); mutex_enter(&tq->tq_lock); ASSERT((tq->tq_task.tqent_next == &tq->tq_task) && (tq->tq_active == 0)); /* notify all the threads that they need to exit */ tq->tq_nthreads_target = 0; tq->tq_flags |= TASKQ_CHANGING; cv_broadcast(&tq->tq_dispatch_cv); cv_broadcast(&tq->tq_exit_cv); while (tq->tq_nthreads != 0) cv_wait(&tq->tq_wait_cv, &tq->tq_lock); if (tq->tq_nthreads_max != 1) kmem_free(tq->tq_threadlist, sizeof (kthread_t *) * tq->tq_nthreads_max); tq->tq_minalloc = 0; while (tq->tq_nalloc != 0) taskq_ent_free(tq, taskq_ent_alloc(tq, TQ_SLEEP)); mutex_exit(&tq->tq_lock); /* * Mark each bucket as closing and wakeup all sleeping threads. */ for (; (b != NULL) && (bid < tq->tq_nbuckets); b++, bid++) { taskq_ent_t *tqe; mutex_enter(&b->tqbucket_lock); b->tqbucket_flags |= TQBUCKET_CLOSE; /* Wakeup all sleeping threads */ for (tqe = b->tqbucket_freelist.tqent_next; tqe != &b->tqbucket_freelist; tqe = tqe->tqent_next) cv_signal(&tqe->tqent_cv); ASSERT(b->tqbucket_nalloc == 0); /* * At this point we waited for all pending jobs to complete (in * both the task queue and the bucket and no new jobs should * arrive. Wait for all threads to die. */ while (b->tqbucket_nfree > 0) cv_wait(&b->tqbucket_cv, &b->tqbucket_lock); mutex_exit(&b->tqbucket_lock); mutex_destroy(&b->tqbucket_lock); cv_destroy(&b->tqbucket_cv); } if (tq->tq_buckets != NULL) { ASSERT(tq->tq_flags & TASKQ_DYNAMIC); kmem_free(tq->tq_buckets, sizeof (taskq_bucket_t) * tq->tq_nbuckets); /* Cleanup fields before returning tq to the cache */ tq->tq_buckets = NULL; tq->tq_tcreates = 0; tq->tq_tdeaths = 0; } else { ASSERT(!(tq->tq_flags & TASKQ_DYNAMIC)); } tq->tq_threads_ncpus_pct = 0; tq->tq_totaltime = 0; tq->tq_tasks = 0; tq->tq_maxtasks = 0; tq->tq_executed = 0; kmem_cache_free(taskq_cache, tq); } /* * Extend a bucket with a new entry on the free list and attach a worker thread * to it. * * Argument: pointer to the bucket. * * This function may quietly fail. It is only used by taskq_dispatch() which * handles such failures properly. */ static void taskq_bucket_extend(void *arg) { taskq_ent_t *tqe; taskq_bucket_t *b = (taskq_bucket_t *)arg; taskq_t *tq = b->tqbucket_taskq; int nthreads; if (! ENOUGH_MEMORY()) { TQ_STAT(b, tqs_nomem); return; } mutex_enter(&tq->tq_lock); /* * Observe global taskq limits on the number of threads. */ if (tq->tq_tcreates++ - tq->tq_tdeaths > tq->tq_maxsize) { tq->tq_tcreates--; mutex_exit(&tq->tq_lock); return; } mutex_exit(&tq->tq_lock); tqe = kmem_cache_alloc(taskq_ent_cache, KM_NOSLEEP); if (tqe == NULL) { mutex_enter(&tq->tq_lock); TQ_STAT(b, tqs_nomem); tq->tq_tcreates--; mutex_exit(&tq->tq_lock); return; } ASSERT(tqe->tqent_thread == NULL); tqe->tqent_bucket = b; /* * Create a thread in a TS_STOPPED state first. If it is successfully * created, place the entry on the free list and start the thread. */ tqe->tqent_thread = thread_create(NULL, 0, taskq_d_thread, tqe, 0, &p0, TS_STOPPED, tq->tq_pri); /* * Once the entry is ready, link it to the the bucket free list. */ mutex_enter(&b->tqbucket_lock); tqe->tqent_func = NULL; TQ_APPEND(b->tqbucket_freelist, tqe); b->tqbucket_nfree++; TQ_STAT(b, tqs_tcreates); #if TASKQ_STATISTIC nthreads = b->tqbucket_stat.tqs_tcreates - b->tqbucket_stat.tqs_tdeaths; b->tqbucket_stat.tqs_maxthreads = MAX(nthreads, b->tqbucket_stat.tqs_maxthreads); #endif mutex_exit(&b->tqbucket_lock); /* * Start the stopped thread. */ thread_lock(tqe->tqent_thread); tqe->tqent_thread->t_taskq = tq; tqe->tqent_thread->t_schedflag |= TS_ALLSTART; setrun_locked(tqe->tqent_thread); thread_unlock(tqe->tqent_thread); } static int taskq_kstat_update(kstat_t *ksp, int rw) { struct taskq_kstat *tqsp = &taskq_kstat; taskq_t *tq = ksp->ks_private; if (rw == KSTAT_WRITE) return (EACCES); tqsp->tq_tasks.value.ui64 = tq->tq_tasks; tqsp->tq_executed.value.ui64 = tq->tq_executed; tqsp->tq_maxtasks.value.ui64 = tq->tq_maxtasks; tqsp->tq_totaltime.value.ui64 = tq->tq_totaltime; tqsp->tq_nactive.value.ui64 = tq->tq_active; tqsp->tq_nalloc.value.ui64 = tq->tq_nalloc; tqsp->tq_pri.value.ui64 = tq->tq_pri; tqsp->tq_nthreads.value.ui64 = tq->tq_nthreads; return (0); } static int taskq_d_kstat_update(kstat_t *ksp, int rw) { struct taskq_d_kstat *tqsp = &taskq_d_kstat; taskq_t *tq = ksp->ks_private; taskq_bucket_t *b = tq->tq_buckets; int bid = 0; if (rw == KSTAT_WRITE) return (EACCES); ASSERT(tq->tq_flags & TASKQ_DYNAMIC); tqsp->tqd_btasks.value.ui64 = tq->tq_tasks; tqsp->tqd_bexecuted.value.ui64 = tq->tq_executed; tqsp->tqd_bmaxtasks.value.ui64 = tq->tq_maxtasks; tqsp->tqd_bnalloc.value.ui64 = tq->tq_nalloc; tqsp->tqd_bnactive.value.ui64 = tq->tq_active; tqsp->tqd_btotaltime.value.ui64 = tq->tq_totaltime; tqsp->tqd_pri.value.ui64 = tq->tq_pri; tqsp->tqd_hits.value.ui64 = 0; tqsp->tqd_misses.value.ui64 = 0; tqsp->tqd_overflows.value.ui64 = 0; tqsp->tqd_tcreates.value.ui64 = 0; tqsp->tqd_tdeaths.value.ui64 = 0; tqsp->tqd_maxthreads.value.ui64 = 0; tqsp->tqd_nomem.value.ui64 = 0; tqsp->tqd_disptcreates.value.ui64 = 0; tqsp->tqd_totaltime.value.ui64 = 0; tqsp->tqd_nalloc.value.ui64 = 0; tqsp->tqd_nfree.value.ui64 = 0; for (; (b != NULL) && (bid < tq->tq_nbuckets); b++, bid++) { tqsp->tqd_hits.value.ui64 += b->tqbucket_stat.tqs_hits; tqsp->tqd_misses.value.ui64 += b->tqbucket_stat.tqs_misses; tqsp->tqd_overflows.value.ui64 += b->tqbucket_stat.tqs_overflow; tqsp->tqd_tcreates.value.ui64 += b->tqbucket_stat.tqs_tcreates; tqsp->tqd_tdeaths.value.ui64 += b->tqbucket_stat.tqs_tdeaths; tqsp->tqd_maxthreads.value.ui64 += b->tqbucket_stat.tqs_maxthreads; tqsp->tqd_nomem.value.ui64 += b->tqbucket_stat.tqs_nomem; tqsp->tqd_disptcreates.value.ui64 += b->tqbucket_stat.tqs_disptcreates; tqsp->tqd_totaltime.value.ui64 += b->tqbucket_totaltime; tqsp->tqd_nalloc.value.ui64 += b->tqbucket_nalloc; tqsp->tqd_nfree.value.ui64 += b->tqbucket_nfree; } return (0); }