From: Chuck Lever <chuck.lever@oracle.com>
To: Jeff Layton <jlayton@kernel.org>, Mike Snitzer <snitzer@kernel.org>
Cc: linux-nfs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-block@vger.kernel.org, Jens Axboe <axboe@kernel.dk>
Subject: Re: A comparison of the new nfsd iomodes (and an experimental one)
Date: Fri, 27 Mar 2026 09:19:07 -0400 [thread overview]
Message-ID: <43921656-e0c3-4b55-ad1f-4965ff40f1f4@oracle.com> (raw)
In-Reply-To: <70e9c23a97d94a3dad5aa7f03f5a22c0950b00bf.camel@kernel.org>
On 3/27/26 7:32 AM, Jeff Layton wrote:
> On Thu, 2026-03-26 at 16:48 -0400, Mike Snitzer wrote:
>
>> Your bandwidth for 1MB sequential IO of 793 MB/s for O_DIRECT and
>> 4,952 MB/s for buffered and dontcache is considerably less than the 72
>> GB/s offered in Jon's testbed. Your testing isn't exposing the
>> bottlenecks (contention) of the MM subsystem for buffered IO... not
>> yet put my finger on _why_ that is.
>
> That may very well be, but not everyone has a box as large as the one
> you and Jon were working with.
Right, and this is kind of a blocker for us. Practically speaking, Jon's
results are not reproducible.
It would be immensely helpful if the MM-tipover behavior could be
reproduced on smaller systems. Reduced physical memory size, lower
network and storage speed, and so on, so that Jeff and I can study the
issue on our own systems.
--
Chuck Lever
next prev parent reply other threads:[~2026-03-27 13:19 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-26 15:23 A comparison of the new nfsd iomodes (and an experimental one) Jeff Layton
2026-03-26 15:30 ` Chuck Lever
2026-03-26 16:35 ` Jeff Layton
2026-03-26 20:48 ` Mike Snitzer
2026-03-27 11:32 ` Jeff Layton
2026-03-27 13:19 ` Chuck Lever [this message]
2026-03-27 16:57 ` Mike Snitzer
2026-03-28 12:37 ` Jeff Layton
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