From: Chuck Lever <chuck.lever@oracle.com>
To: Jeff Layton <jlayton@kernel.org>,
linux-nfs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-block@vger.kernel.org
Cc: Mike Snitzer <snitzer@kernel.org>, Jens Axboe <axboe@kernel.dk>
Subject: Re: A comparison of the new nfsd iomodes (and an experimental one)
Date: Thu, 26 Mar 2026 11:30:55 -0400 [thread overview]
Message-ID: <d453add6-ed23-4d61-af95-d80133b0e456@oracle.com> (raw)
In-Reply-To: <4ebbd194ccfb3bcea6225d926b4c9f339e21c813.camel@kernel.org>
On 3/26/26 11:23 AM, Jeff Layton wrote:
> I've been doing some benchmarking of the new nfsd iomodes, using
> different fio-based workloads.
>
> The results have been interesting, but one thing that stands out is
> that RWF_DONTCACHE is absolutely terrible for streaming write
> workloads. That prompted me to experiment with a new iomode that added
> some optimizations (DONTCACHE_LAZY).
>
> The results along with Claude's analysis are here:
>
> https://markdownpastebin.com/?id=387375d00b5443b3a2e37d58a062331f
>
> He gets a bit out over his skis on the upstream plan, but tl;dr is that
> DONTCACHE_LAZY (which is DONTCACHE with some optimizations) outperforms
> the other write iomodes.
The analysis of the write modes seems plausible. I'm interested to hear
what Mike and Jens have to say about that.
One thing I'd like to hear more about is why Claude felt that disabling
splice read was beneficial. My own benchmarking in that area has shown
that splice read is always a win over not using splice.
--
Chuck Lever
next prev parent reply other threads:[~2026-03-26 15:31 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 [this message]
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
2026-03-27 16:57 ` Mike Snitzer
2026-03-28 12:37 ` Jeff Layton
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