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From: Chuck Lever III <chuck.lever@oracle.com>
To: Tejun Heo <tj@kernel.org>
Cc: open list <linux-kernel@vger.kernel.org>,
	Linux NFS Mailing List <linux-nfs@vger.kernel.org>
Subject: contention on pwq->pool->lock under heavy NFS workload
Date: Wed, 21 Jun 2023 15:26:22 +0000	[thread overview]
Message-ID: <38FA0353-5303-4A3D-86A5-EF1E989CD497@oracle.com> (raw)

Hi Tejun-

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?

Thanks in advance.

--
Chuck Lever



             reply	other threads:[~2023-06-21 15:26 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-06-21 15:26 Chuck Lever III [this message]
2023-06-21 21:28 ` contention on pwq->pool->lock under heavy NFS workload Tejun Heo
2023-06-22 14:38   ` Chuck Lever III
2023-06-22 15:45   ` Chuck Lever III
2023-06-22 19:23     ` Tejun Heo
2023-06-22 19:39       ` Chuck Lever III
2023-06-23 14:37         ` Chuck Lever III
2023-06-24  1:44           ` Tejun Heo
2023-06-25 16:01             ` Chuck Lever III
2023-06-26 20:21               ` Tejun Heo

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