Changes in test_workqueue.c

7de6b4a246330fe29fa2fd144b4724ca35d60d6c - Merge tag 'wq-for-7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq

Wed, 15 Apr 2026 19:32:08 +0200

Merge tag 'wq-for-7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wqPull workqueue updates from Tejun Heo: - New default WQ_AFFN_CACHE_SHARD affinity scope subdivides LLCs into smaller shards to improve scalability on machines with many CPUs per LLC - Misc: - system_dfl_long_wq for long unbound works - devm_alloc_workqueue() for device-managed allocation - sysfs exposure for ordered workqueues and the EFI workqueue - removal of HK_TYPE_WQ from wq_unbound_cpumask - various small fixes* tag 'wq-for-7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq: (21 commits) workqueue: validate cpumask_first() result in llc_populate_cpu_shard_id() workqueue: use NR_STD_WORKER_POOLS instead of hardcoded value workqueue: avoid unguarded 64-bit division docs: workqueue: document WQ_AFFN_CACHE_SHARD affinity scope workqueue: add test_workqueue benchmark module tools/workqueue: add CACHE_SHARD support to wq_dump.py workqueue: set WQ_AFFN_CACHE_SHARD as the default affinity scope workqueue: add WQ_AFFN_CACHE_SHARD affinity scope workqueue: fix typo in WQ_AFFN_SMT comment workqueue: Remove HK_TYPE_WQ from affecting wq_unbound_cpumask workqueue: unlink pwqs from wq->pwqs list in alloc_and_link_pwqs() error path workqueue: Remove NULL wq WARN in __queue_delayed_work() workqueue: fix parse_affn_scope() prefix matching bug workqueue: devres: Add device-managed allocate workqueue workqueue: Add system_dfl_long_wq for long unbound works tools/workqueue/wq_dump.py: add NODE prefix to all node columns tools/workqueue/wq_dump.py: fix column alignment in node_nr/max_active section tools/workqueue/wq_dump.py: remove backslash separator from node_nr/max_active header efi: Allow to expose the workqueue via sysfs workqueue: Allow to expose ordered workqueues via sysfs ... List of files: /linux/lib/test_workqueue.c

c6890f36fc49848c61d2113a3442eb1b59e0bc4b - workqueue: avoid unguarded 64-bit division

Thu, 02 Apr 2026 22:59:03 +0200

workqueue: avoid unguarded 64-bit divisionThe printk() requires a division that is not allowed on 32-bit architectures:x86_64-linux-ld: lib/test_workqueue.o: in function `test_workqueue_init':test_workqueue.c:(.init.text+0x36f): undefined reference to `__udivdi3'Use div_u64() to print the resulting elapsed microseconds.Fixes: 24b2e73f9700 ("workqueue: add test_workqueue benchmark module")Signed-off-by: Arnd Bergmann Signed-off-by: Tejun Heo List of files: /linux/lib/test_workqueue.c

24b2e73f9700e0682575feb34556b756e59d4548 - workqueue: add test_workqueue benchmark module

Wed, 01 Apr 2026 15:03:56 +0200

workqueue: add test_workqueue benchmark moduleAdd a kernel module that benchmarks queue_work() throughput on anunbound workqueue to measure pool->lock contention under differentaffinity scope configurations (cache vs cache_shard).The module spawns N kthreads (default: num_online_cpus()), each boundto a different CPU. All threads start simultaneously and queue workitems, measuring the latency of each queue_work() call. Results arereported as p50/p90/p95 latencies for each affinity scope.The affinity scope is switched between runs via the workqueue's sysfsaffinity_scope attribute (WQ_SYSFS), avoiding the need for any newexported symbols.The module runs as __init-only, returning -EAGAIN to auto-unload,and can be re-run via insmod.Example of the output: running 50 threads, 50000 items/thread cpu 6806017 items/sec p50=2574 p90=5068 p95=5818 ns smt 6821040 items/sec p50=2624 p90=5168 p95=5949 ns cache_shard 1633653 items/sec p50=5337 p90=9694 p95=11207 ns cache 286069 items/sec p50=72509 p90=82304 p95=85009 ns numa 319403 items/sec p50=63745 p90=73480 p95=76505 ns system 308461 items/sec p50=66561 p90=75714 p95=78048 nsSigned-off-by: Breno Leitao Signed-off-by: Tejun Heo List of files: /linux/lib/test_workqueue.c