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From: Christoph Hellwig <hch@infradead.org>
To: NeilBrown <neilb@suse.de>
Cc: Trond Myklebust <trondmy@hammerspace.com>,
	"david@fromorbit.com" <david@fromorbit.com>,
	"bfoster@redhat.com" <bfoster@redhat.com>,
	"snitzer@kernel.org" <snitzer@kernel.org>,
	"linux-nfs@vger.kernel.org" <linux-nfs@vger.kernel.org>,
	"linux-xfs@vger.kernel.org" <linux-xfs@vger.kernel.org>
Subject: Re: [PATCH v2] xfs: enable WQ_MEM_RECLAIM on m_sync_workqueue
Date: Fri, 5 Jul 2024 23:13:20 -0700	[thread overview]
Message-ID: <ZojggALtQ3kqaJJo@infradead.org> (raw)
In-Reply-To: <172022597256.11489.7372525202519871550@noble.neil.brown.name>

On Sat, Jul 06, 2024 at 10:32:52AM +1000, NeilBrown wrote:
> Would it be reasonable for the partial pages to be written over RPC and
> for only full pages to be sent directly to the server-side file using
> O_DIRECT writes?  Presumably the benefits of localio are most pronounced
> with large writes which will mostly be full-page, or even full-folio.

Yes.  Note that we already have infrastructure to always read the
entire page for pnfs block (PNFS_READ_WHOLE_PAGE /
pnfs_ld_read_whole_page) to make this a lot more common at least for
reads.

> O_DIRECT writes on the NFS side would be more awkward.  open(2)
> documents that NFS places no alignment restrictions on O_DIRECT I/O.  If
> applications depend on that then some copying will have to be done
> before the data is written to a block filesystem - possibly into the
> page cache, possibly into some other buffer.  This wouldn't be more
> copying that we already do.

Yes.  There is precedence for that in pNFS as well:
fs/nfs/blocklayout/blocklayout.c:is_aligned_req().


  reply	other threads:[~2024-07-06  6:13 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-06-28 16:18 [RFC PATCH] xfs: enable WQ_MEM_RECLAIM on m_sync_workqueue Mike Snitzer
2024-06-30 16:35 ` [PATCH v2] " Mike Snitzer
2024-06-30 23:46   ` Dave Chinner
2024-07-01  4:45     ` Christoph Hellwig
2024-07-02 23:51       ` Dave Chinner
2024-07-03 11:29       ` NeilBrown
2024-07-03 14:15         ` Christoph Hellwig
2024-07-03 23:02           ` Dave Chinner
2024-07-09 23:12           ` NeilBrown
2024-07-11 11:55             ` Dave Chinner
2024-07-01 14:13     ` Mike Snitzer
2024-07-02 12:33       ` Trond Myklebust
2024-07-02 13:04         ` Dave Chinner
2024-07-02 14:00           ` Trond Myklebust
2024-07-02 23:15             ` Dave Chinner
2024-07-06  0:32             ` NeilBrown
2024-07-06  6:13               ` Christoph Hellwig [this message]
2024-07-06  6:37                 ` Christoph Hellwig
2024-07-09 23:39                   ` NeilBrown

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