From: Christoph Hellwig <hch@infradead.org>
To: Chuck Lever <chuck.lever@oracle.com>
Cc: Jeff Layton <jlayton@kernel.org>,
Mike Snitzer <snitzer@kernel.org>,
linux-nfs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
Jens Axboe <axboe@kernel.dk>
Subject: Re: [PATCH 5/6] NFSD: leverage DIO alignment to selectively issue O_DIRECT reads and writes
Date: Thu, 12 Jun 2025 00:28:42 -0700 [thread overview]
Message-ID: <aEqBqlLErTQ0ZNYZ@infradead.org> (raw)
In-Reply-To: <27bc1d2d-7cc8-449c-9e4c-3a515631fa87@oracle.com>
On Wed, Jun 11, 2025 at 11:11:28AM -0400, Chuck Lever wrote:
> > If we're doing synchronous, direct I/O writes then why not just respond
> > with FILE_SYNC? The write should be on the platter by the time it
> > returns.
>
> Because "platter". On some devices, writes are slow.
>
> For some workloads, unstable is faster. I have an experimental series
> that makes NFSD convert all NFS WRITEs to FILE_SYNC. It was not an
> across the board win, even with an NVMe-backed file system.
For everything that is not a pure overwrite on a file system that passes
them through, and a device not having a volatile write cache FILE_SYNC
currently is slower. That might change for file systems logging
synchronous writes (I'm playing with that for XFS a bit again), but even
then you only want to selectively do that when the client specifically
requests O_DSYNC semantics as you'd easily overwhelm the log and
introduce a log write amplification.
next prev parent reply other threads:[~2025-06-12 7:28 UTC|newest]
Thread overview: 75+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-06-10 20:57 [PATCH 0/6] NFSD: add enable-dontcache and initially use it to add DIO support Mike Snitzer
2025-06-10 20:57 ` [PATCH 1/6] NFSD: add the ability to enable use of RWF_DONTCACHE for all IO Mike Snitzer
2025-06-11 6:57 ` Christoph Hellwig
2025-06-11 10:44 ` Mike Snitzer
2025-06-11 13:04 ` Jeff Layton
2025-06-11 13:56 ` Chuck Lever
2025-06-11 14:31 ` Chuck Lever
2025-06-11 19:18 ` Mike Snitzer
2025-06-11 20:29 ` Jeff Layton
2025-06-11 21:36 ` need SUNRPC TCP to receive into aligned pages [was: Re: [PATCH 1/6] NFSD: add the ability to enable use of RWF_DONTCACHE for all IO] Mike Snitzer
2025-06-12 10:28 ` Jeff Layton
2025-06-12 11:28 ` Jeff Layton
2025-06-12 13:28 ` Chuck Lever
2025-06-12 14:17 ` Benjamin Coddington
2025-06-12 15:56 ` Mike Snitzer
2025-06-12 15:58 ` Chuck Lever
2025-06-12 16:12 ` Mike Snitzer
2025-06-12 16:32 ` Chuck Lever
2025-06-13 5:39 ` Christoph Hellwig
2025-06-12 16:22 ` Jeff Layton
2025-06-13 5:46 ` Christoph Hellwig
2025-06-13 9:23 ` Mike Snitzer
2025-06-13 13:02 ` Jeff Layton
2025-06-16 12:35 ` Christoph Hellwig
2025-06-16 12:29 ` Christoph Hellwig
2025-06-16 16:07 ` Mike Snitzer
2025-06-17 4:37 ` Christoph Hellwig
2025-06-17 20:26 ` Mike Snitzer
2025-06-17 22:23 ` [RFC PATCH] lib/iov_iter: remove piecewise bvec length checking in iov_iter_aligned_bvec [was: Re: need SUNRPC TCP to receive into aligned pages] Mike Snitzer
2025-07-03 0:12 ` need SUNRPC TCP to receive into aligned pages [was: Re: [PATCH 1/6] NFSD: add the ability to enable use of RWF_DONTCACHE for all IO] NeilBrown
2025-06-12 7:13 ` [PATCH 1/6] NFSD: add the ability to enable use of RWF_DONTCACHE for all IO Christoph Hellwig
2025-06-12 13:15 ` Chuck Lever
2025-06-12 13:21 ` Chuck Lever
2025-06-12 16:00 ` Mike Snitzer
2025-06-16 13:32 ` Chuck Lever
2025-06-16 16:10 ` Mike Snitzer
2025-06-17 17:22 ` Mike Snitzer
2025-06-17 17:31 ` Chuck Lever
2025-06-19 20:19 ` Mike Snitzer
2025-06-30 14:50 ` Chuck Lever
2025-07-04 19:46 ` Mike Snitzer
2025-07-04 19:49 ` Chuck Lever
2025-06-10 20:57 ` [PATCH 2/6] NFSD: filecache: add STATX_DIOALIGN and STATX_DIO_READ_ALIGN support Mike Snitzer
2025-06-10 20:57 ` [PATCH 3/6] NFSD: pass nfsd_file to nfsd_iter_read() Mike Snitzer
2025-06-10 20:57 ` [PATCH 4/6] fs: introduce RWF_DIRECT to allow using O_DIRECT on a per-IO basis Mike Snitzer
2025-06-11 6:58 ` Christoph Hellwig
2025-06-11 10:51 ` Mike Snitzer
2025-06-11 14:17 ` Chuck Lever
2025-06-12 7:15 ` Christoph Hellwig
2025-06-10 20:57 ` [PATCH 5/6] NFSD: leverage DIO alignment to selectively issue O_DIRECT reads and writes Mike Snitzer
2025-06-11 7:00 ` Christoph Hellwig
2025-06-11 12:23 ` Mike Snitzer
2025-06-11 13:30 ` Jeff Layton
2025-06-12 7:22 ` Christoph Hellwig
2025-06-12 7:23 ` Christoph Hellwig
2025-06-11 14:42 ` Chuck Lever
2025-06-11 15:07 ` Jeff Layton
2025-06-11 15:11 ` Chuck Lever
2025-06-11 15:44 ` Jeff Layton
2025-06-11 20:51 ` Mike Snitzer
2025-06-12 7:32 ` Christoph Hellwig
2025-06-12 7:28 ` Christoph Hellwig [this message]
2025-06-12 7:25 ` Christoph Hellwig
2025-06-10 20:57 ` [PATCH 6/6] NFSD: issue READs using O_DIRECT even if IO is misaligned Mike Snitzer
2025-06-11 12:55 ` [PATCH 0/6] NFSD: add enable-dontcache and initially use it to add DIO support Jeff Layton
2025-06-12 7:39 ` Christoph Hellwig
2025-06-12 20:37 ` Mike Snitzer
2025-06-13 5:31 ` Christoph Hellwig
2025-06-11 14:16 ` Chuck Lever
2025-06-11 18:02 ` Mike Snitzer
2025-06-11 19:06 ` Chuck Lever
2025-06-11 19:58 ` Mike Snitzer
2025-06-12 13:46 ` Chuck Lever
2025-06-12 19:08 ` Mike Snitzer
2025-06-12 20:17 ` Chuck Lever
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