Finishing touches to fork1() - ANSIfy missed function definition, style(9)
fixes, removal of few comments that didn't really make sense and addition
of fork_findpid() locking requirements.

Refactor fork1() to make it easier to follow. No functional changes.

Reviewed by: kib (earlier version)
Tested by: pho

Sync: merge r216133 through r216338 from ^/head.

MFp4:
It is possible a lower priority thread lending priority to higher priority
thread, in old code, it is ignored, however the lending should always be
recorded, add field td_lend_user_pri to fix t

MFp4:
It is possible a lower priority thread lending priority to higher priority
thread, in old code, it is ignored, however the lending should always be
recorded, add field td_lend_user_pri to fix the problem, if a thread does
not have borrowed priority, its value is PRI_MAX.

MFC after: 1 week

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Add a KASSERT to make it obvious when fork_norfproc() is to be called,
and set *procp to NULL in all cases. Previously, it was not being set
in the ERESTART case. This is effectively no-op, since i

Add a KASSERT to make it obvious when fork_norfproc() is to be called,
and set *procp to NULL in all cases. Previously, it was not being set
in the ERESTART case. This is effectively no-op, since its value is
ignored by callers in the error case.

Reviewed by: kib@

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Fix style bug introduced by previous commit.

Improve readability by factoring out the !RFPROC case. While here,
turn K&R function definitions into ANSI. No functional changes.

Reviewed by: kib@

Merge svn+ssh://svn.freebsd.org/base/head@214309

Sync: merge r214077 through r214219 from ^/head.

- When disabling ktracing on a process, free any pending requests that
may be left. This fixes a memory leak that can occur when tracing is
disabled on a process via disabling tracing of a speci

- When disabling ktracing on a process, free any pending requests that
may be left. This fixes a memory leak that can occur when tracing is
disabled on a process via disabling tracing of a specific file (or if
an I/O error occurs with the tracefile) if the process's next system
call is exit(). The trace disabling code clears p_traceflag, so exit1()
doesn't do any KTRACE-related cleanup leading to the leak. I chose to
make the free'ing of pending records synchronous rather than patching
exit1().
- Move KTRACE-specific logic out of kern_(exec|exit|fork).c and into
kern_ktrace.c instead. Make ktrace_mtx private to kern_ktrace.c as a
result.

MFC after: 1 month

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Create a global thread hash table to speed up thread lookup, use
rwlock to protect the table. In old code, thread lookup is done with
process lock held, to find a thread, kernel has to iterate throug

Create a global thread hash table to speed up thread lookup, use
rwlock to protect the table. In old code, thread lookup is done with
process lock held, to find a thread, kernel has to iterate through
process and thread list, this is quite inefficient.
With this change, test shows in extreme case performance is
dramatically improved.

Earlier patch was reviewed by: jhb, julian

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Fix two bugs in DTrace:
* when the process exits, remove the associated USDT probes
* when the process forks, duplicate the USDT probes.

Sponsored by: The FreeBSD Foundation

Add an extra comment to the SDT probes definition. This allows us to get
use '-' in probe names, matching the probe names in Solaris.[1]

Add userland SDT probes definitions to sys/sdt.h.

Sponsored

Add an extra comment to the SDT probes definition. This allows us to get
use '-' in probe names, matching the probe names in Solaris.[1]

Add userland SDT probes definitions to sys/sdt.h.

Sponsored by: The FreeBSD Foundation
Discussed with: rwaston [1]

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MFC r207468:
Extract thread_lock()/ruxagg()/thread_unlock() fragment into utility
function ruxagg_tlock().
Convert the definition of kern_getrusage() to ANSI C.

MFC r207602:
Implement RUSAGE_THREAD.

MFC r207468:
Extract thread_lock()/ruxagg()/thread_unlock() fragment into utility
function ruxagg_tlock().
Convert the definition of kern_getrusage() to ANSI C.

MFC r207602:
Implement RUSAGE_THREAD. Add td_rux to keep extended runtime and ticks
information for thread to allow calcru1() (re)use.

Rename ruxagg()->ruxagg_locked(), ruxagg_tlock()->ruxagg() [1].
The ruxagg_locked() function no longer clears thread ticks nor
td_incruntime.

Not an MFC: the td_rux is added to the end of struct thread to keep
the KBI. Explicit bzero() of td_rux is added to new thread initialization
points.

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Merge from head

Merge from head up to r188941 (last revision before the USB stack switch)

- MFC from head@196987

MFC r196730:
Remove the altkstacks, instead instantiate threads with kernel stack
allocated with the right size from the start. For the thread that has
kernel stack cached, verify that requested stac

MFC r196730:
Remove the altkstacks, instead instantiate threads with kernel stack
allocated with the right size from the start. For the thread that has
kernel stack cached, verify that requested stack size is equial to the
actual, and reallocate the stack if sizes differ.

Introduce separate kernel stack cache that keeps some limited amount of
preallocated kernel stacks to lower the latency of thread allocation.

Not a merge: instead of removing td_altkstack* members of struct thread,
replace them with placeholders to keep struct thread layout on the
stable branch.

Also, record r196640, r196644 and r196648 as merged.

Approved by: re (kensmith)

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Reintroduce the r196640, after fixing the problem with my testing.

Remove the altkstacks, instead instantiate threads with kernel stack
allocated with the right size from the start. For the thread t

Reintroduce the r196640, after fixing the problem with my testing.

Remove the altkstacks, instead instantiate threads with kernel stack
allocated with the right size from the start. For the thread that has
kernel stack cached, verify that requested stack size is equial to the
actual, and reallocate the stack if sizes differ [1].

This fixes the bug introduced by r173361 that was committed several days
after r173004 and consisted of kthread_add(9) ignoring the non-default
kernel stack size.

Also, r173361 removed the caching of the kernel stacks for a non-first
thread in the process. Introduce separate kernel stack cache that keeps
some limited amount of preallocated kernel stacks to lower the latency
of thread allocation. Add vm_lowmem handler to prune the cache on
low memory condition. This way, system with reasonable amount of the
threads get lower latency of thread creation, while still not exhausting
significant portion of KVA for unused kstacks.

Submitted by: peter [1]
Discussed with: jhb, julian, peter
Reviewed by: jhb
Tested by: pho (and retested according to new test scenarious)
MFC after: 1 week

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Reverse r196640 and r196644 for now.

Dispose the kernel stack of the proper thread.

Submitted by: alc
MFC after: 1 week

Remove the altkstacks, instead instantiate threads with kernel stack
allocated with the right size from the start. For the thread that has
kernel stack cached, verify that requested stack size is equ

Remove the altkstacks, instead instantiate threads with kernel stack
allocated with the right size from the start. For the thread that has
kernel stack cached, verify that requested stack size is equial to the
actual, and reallocate the stack if sizes differ [1].

This fixes the bug introduced by r173361 that was committed several days
after r173004 and consisted of kthread_add(9) ignoring the non-default
kernel stack size.

Also, r173361 removed the caching of the kernel stacks for a non-first
thread in the process. Introduce separate kernel stack cache that keeps
some limited amount of preallocated kernel stacks to lower the latency
of thread allocation. Add vm_lowmem handler to prune the cache on
low memory condition. This way, system with reasonable amount of the
threads get lower latency of thread creation, while still not exhausting
significant portion of KVA for unused kstacks.

Submitted by: peter [1]
Discussed with: jhb, julian, peter
Reviewed by: jhb
Tested by: pho
MFC after: 1 week

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- MFC @196061

Remove the interim vimage containers, struct vimage and struct procg,
and the ioctl-based interface that supported them.

Approved by: re (kib), bz (mentor)

- MFC