Hello, On Wed, Jun 21, 2023 at 03:26:22PM +0000, Chuck Lever III wrote: > lock_stat reports that the pool->lock kernel/workqueue.c:1483 is the highest > contended lock on my test NFS client. The issue appears to be that the three > NFS-related workqueues, rpciod_workqueue, xprtiod_workqueue, and nfsiod all > get placed in the same worker_pool, so they have to fight over one pool lock. > > I notice that ib_comp_wq is allocated with the same flags, but I don't see > significant contention there, and a trace_printk in __queue_work shows that > work items queued on that WQ seem to alternate between at least two different > worker_pools. > > Is there a preferred way to ensure the NFS WQs get spread a little more fairly > amongst the worker_pools? Can you share the output of lstopo on the test machine? The following branch has pending workqueue changes which makes unbound workqueues finer grained by default and a lot more flexible in how they're segmented. git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq.git affinity-scopes-v2 Can you please test with the brnach? If the default doesn't improve the situation, you can set WQ_SYSFS on the affected workqueues and change their scoping by writing to /sys/devices/virtual/WQ_NAME/affinity_scope. Please take a look at https://git.kernel.org/pub/scm/linux/kernel/git/tj/wq.git/tree/Documentation/core-api/workqueue.rst?h=affinity-scopes-v2#n350 for more details. Thanks. -- tejun
