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

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Date:   Wed, 29 Nov 2023 12:43:36 +0100
From:   Christian Brauner <brauner@...nel.org>
To:     NeilBrown <neilb@...e.de>
Cc:     Al Viro <viro@...iv.linux.org.uk>,
        Jeff Layton <jlayton@...nel.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.

> If an nfsd thread only completes the close that it initiated the close
> on (which is what I am currently proposing) then there would be at most
> one, or maybe 2, fds to close after handling each request.  While that
> is certainly a non-zero burden, I can't see how it can realistically be
> called a DOS.

The 10s of millions of files is what makes me curious. Because that's
the workload that'd be interesting.

> > It feels that this really needs to be tested under a similar workload in
> > question to see whether this is a viable solution.
> > 
> 
> Creating that workload might be a challenge.  I know it involved
> accessing 10s of millions of files with a server that was somewhat
> memory constrained.  I don't know anything about the access pattern.
> 
> Certainly I'll try to reproduce something similar by inserting delays in
> suitable places.  This will help exercise the code, but won't really
> replicate the actual workload.