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Date: Tue, 28 Nov 2023 15:01:57 +0100
From: Oleg Nesterov <oleg@redhat.com>
To: NeilBrown <neilb@suse.de>, Al Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>, Jens Axboe <axboe@kernel.dk>,
	Chuck Lever <chuck.lever@oracle.com>,
	Jeff Layton <jlayton@kernel.org>, Ingo Molnar <mingo@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Juri Lelli <juri.lelli@redhat.com>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-nfs@vger.kernel.org
Subject: Re: [PATCH/RFC] core/nfsd: allow kernel threads to use task_work.
Message-ID: <20231128140156.GC22743@redhat.com>
References: <170112272125.7109.6245462722883333440@noble.neil.brown.name>
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On 11/28, NeilBrown wrote:
>
> I have evidence from a customer site of 256 nfsd threads adding files to
> delayed_fput_lists nearly twice as fast they are retired by a single
> work-queue thread running delayed_fput().  As you might imagine this
> does not end well (20 million files in the queue at the time a snapshot
> was taken for analysis).

On a related note... Neil, Al, et al, can you look at

	[PATCH 1/3] fput: don't abuse task_work_add() when possible
	https://lore.kernel.org/all/20150908171446.GA14589@redhat.com/

(please ignore 3/3).

Oleg.