From: "Darrick J. Wong" <email@example.com> To: Dave Chinner <firstname.lastname@example.org> Cc: Christoph Hellwig <email@example.com>, firstname.lastname@example.org, email@example.com, firstname.lastname@example.org Subject: Re: [PATCH 01/16] xfs: drop ->writepage completely Date: Tue, 2 Feb 2021 12:51:56 -0800 [thread overview] Message-ID: <20210202205156.GU7193@magnolia> (raw) In-Reply-To: <20181112210839.GM19305@dastard> On Tue, Nov 13, 2018 at 08:08:39AM +1100, Dave Chinner wrote: > On Fri, Nov 09, 2018 at 07:12:39AM -0800, Christoph Hellwig wrote: > > [adding linux-mm to the CC list] > > > > On Wed, Nov 07, 2018 at 05:31:12PM +1100, Dave Chinner wrote: > > > From: Dave Chinner <email@example.com> > > > > > > ->writepage is only used in one place - single page writeback from > > > memory reclaim. We only allow such writeback from kswapd, not from > > > direct memory reclaim, and so it is rarely used. When it comes from > > > kswapd, it is effectively random dirty page shoot-down, which is > > > horrible for IO patterns. We will already have background writeback > > > trying to clean all the dirty pages in memory as efficiently as > > > possible, so having kswapd interrupt our well formed IO stream only > > > slows things down. So get rid of xfs_vm_writepage() completely. > > > > Interesting. IFF we can pull this off it would simplify a lot of > > things, so I'm generally in favor of it. > > Over the past few days of hammeringon this, the only thing I've > noticed is that page reclaim hangs up less, but it's also putting a > bit more pressure on the shrinkers. Filesystem intensive workloads > that drive the machine into reclaim via the page cache seem to hit > breakdown conditions slightly earlier and the impact is that the > shrinkers are run harder. Mostly I see this as the XFS buffer cache > having a much harder time keeping a working set active. > > However, while the workloads hit the working set cache, writeback > performance does seem to be slightly higher. It is, however, being > offset by the deeper lows that come from the cache being turned > over. > > So there's a bit of rebalancing to be done here as a followup, but > I've been unable to drive the system into unexepected OOM kills or > other bad behaviour as a result of removing ->writepage. FWIW I've been running this patch in my development kernels as part of exercising realtime reflink with rextsize > 1. So far I haven't seen any particularly adverse effects. --D > > Cheers, > > Dave. > -- > Dave Chinner > firstname.lastname@example.org
next prev parent reply other threads:[~2021-02-02 20:52 UTC|newest] Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-11-07 6:31 [RFC PATCH 00/16] xfs: Block size > PAGE_SIZE support Dave Chinner 2018-11-07 6:31 ` [PATCH 01/16] xfs: drop ->writepage completely Dave Chinner 2018-11-09 15:12 ` Christoph Hellwig 2018-11-12 21:08 ` Dave Chinner 2021-02-02 20:51 ` Darrick J. Wong [this message] 2018-11-07 6:31 ` [PATCH 02/16] xfs: move writepage context warnings to writepages Dave Chinner 2018-11-07 6:31 ` [PATCH 03/16] xfs: finobt AG reserves don't consider last AG can be a runt Dave Chinner 2018-11-07 16:55 ` Darrick J. Wong 2018-11-09 0:21 ` Dave Chinner 2018-11-07 6:31 ` [PATCH 04/16] xfs: extent shifting doesn't fully invalidate page cache Dave Chinner 2018-11-07 6:31 ` [PATCH 05/16] iomap: sub-block dio needs to zeroout beyond EOF Dave Chinner 2018-11-09 15:15 ` Christoph Hellwig 2018-11-07 6:31 ` [PATCH 06/16] iomap: support block size > page size for direct IO Dave Chinner 2018-11-08 11:28 ` Nikolay Borisov 2018-11-09 15:18 ` Christoph Hellwig 2018-11-11 1:12 ` Dave Chinner 2018-11-07 6:31 ` [PATCH 07/16] iomap: prepare buffered IO paths for block size > page size Dave Chinner 2018-11-09 15:19 ` Christoph Hellwig 2018-11-11 1:15 ` Dave Chinner 2018-11-07 6:31 ` [PATCH 08/16] iomap: mode iomap_zero_range and friends Dave Chinner 2018-11-09 15:19 ` Christoph Hellwig 2018-11-07 6:31 ` [PATCH 09/16] iomap: introduce zero-around functionality Dave Chinner 2018-11-07 6:31 ` [PATCH 10/16] iomap: enable zero-around for iomap_zero_range() Dave Chinner 2018-11-07 6:31 ` [PATCH 11/16] iomap: Don't mark partial pages zeroing uptodate for zero-around Dave Chinner 2018-11-07 6:31 ` [PATCH 12/16] iomap: zero-around in iomap_page_mkwrite Dave Chinner 2018-11-07 6:31 ` [PATCH 13/16] xfs: add zero-around controls to iomap Dave Chinner 2018-11-07 6:31 ` [PATCH 14/16] xfs: align writepages to large block sizes Dave Chinner 2018-11-09 15:22 ` Christoph Hellwig 2018-11-11 1:20 ` Dave Chinner 2018-11-11 16:32 ` Christoph Hellwig 2018-11-14 14:19 ` Brian Foster 2018-11-14 21:18 ` Dave Chinner 2018-11-15 12:55 ` Brian Foster 2018-11-16 6:19 ` Dave Chinner 2018-11-16 13:29 ` Brian Foster 2018-11-19 1:14 ` Dave Chinner 2018-11-07 6:31 ` [PATCH 15/16] xfs: expose block size in stat Dave Chinner 2018-11-07 6:31 ` [PATCH 16/16] xfs: enable block size larger than page size support Dave Chinner 2018-11-07 17:14 ` [RFC PATCH 00/16] xfs: Block size > PAGE_SIZE support Darrick J. Wong 2018-11-07 22:04 ` Dave Chinner 2018-11-08 1:38 ` Darrick J. Wong 2018-11-08 9:04 ` Dave Chinner 2018-11-08 22:17 ` Darrick J. Wong 2018-11-08 22:22 ` Dave Chinner
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=20210202205156.GU7193@magnolia \ --email@example.com \ --firstname.lastname@example.org \ --email@example.com \ --firstname.lastname@example.org \ --email@example.com \ --firstname.lastname@example.org \ --subject='Re: [PATCH 01/16] xfs: drop ->writepage completely' \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: link
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for NNTP newsgroup(s).