linux-kernel - Re: [PATCH/RFC] core/nfsd: allow kernel threads to use task

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Message-ID: <20231128140156.GC22743@redhat.com>
Date:   Tue, 28 Nov 2023 15:01:57 +0100
From:   Oleg Nesterov <oleg@...hat.com>
To:     NeilBrown <neilb@...e.de>, Al Viro <viro@...iv.linux.org.uk>
Cc:     Christian Brauner <brauner@...nel.org>,
        Jens Axboe <axboe@...nel.dk>,
        Chuck Lever <chuck.lever@...cle.com>,
        Jeff Layton <jlayton@...nel.org>,
        Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Juri Lelli <juri.lelli@...hat.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-nfs@...r.kernel.org
Subject: Re: [PATCH/RFC] core/nfsd: allow kernel threads to use task_work.

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.