Re: [PATCH/RFC] core/nfsd: allow kernel threads to use task_work.

From: Christian Brauner <brauner@kernel.org>
To: NeilBrown <neilb@suse.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>,
	Jeff Layton <jlayton@kernel.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.
Date: Wed, 29 Nov 2023 12:43:36 +0100	[thread overview]
Message-ID: <20231129-querschnitt-urfassung-3ebd703c345a@brauner> (raw)
In-Reply-To: <170121362397.7109.17858114692838122621@noble.neil.brown.name>

> 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.