From: Dave Chinner <dgc@kernel.org>
To: Fengnan <changfengnan@bytedance.com>
Cc: Ojaswin Mujoo <ojaswin@linux.ibm.com>,
Fengnan Chang <fengnanchang@gmail.com>,
brauner@kernel.org, djwong@kernel.org, linux-xfs@vger.kernel.org,
linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org,
lidiangang@bytedance.com
Subject: Re: [RFC PATCH] iomap: add fast read path for small direct I/O
Date: Wed, 22 Apr 2026 08:36:37 +1000 [thread overview]
Message-ID: <aef79R24wFemmUdN@dread> (raw)
In-Reply-To: <87674d63-c8cb-4135-8d76-84f52e90ac2e@bytedance.com>
On Tue, Apr 21, 2026 at 11:19:31AM +0800, Fengnan wrote:
> 在 2026/4/21 07:59, Dave Chinner 写道:
> > I'm clearly missing something here. I'm trying to work out why the
> > profiles show what they do, but there's differences between them
> > that do make obvious sense to me.
> >
> > It would also be useful to have XFS profiles, because it has a
> > larger CPU cache footprint than ext4. If what the profiles are
> > showing is a result of CPU cache residency artifacts, then we'll see
> > different profile (and, potentially, performance) artifacts with
> > XFS...
> The XFS flame graph is also attached now.
> IOPS: 1.92M->2.3M.
The callchains in both XFS flame graphs are completely bogus:
<io_uring entry>
....
io_read
__io_read
xfs_inode_free_eofblocks
xfs_prep_free_cowblocks
iomap_dio_rw
iomap_dio_simple_read
xfs_mountfs
....
Can you regenerate the profiles, please, and this time check that
they make sense before posting them?
-Dave.
--
Dave Chinner
dgc@kernel.org
next prev parent reply other threads:[~2026-04-21 22:36 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-14 12:26 [RFC PATCH] iomap: add fast read path for small direct I/O Fengnan Chang
2026-04-15 7:14 ` Christoph Hellwig
2026-04-16 3:16 ` changfengnan
2026-04-17 7:30 ` Christoph Hellwig
2026-04-15 19:06 ` Ojaswin Mujoo
2026-04-16 3:22 ` changfengnan
2026-04-18 19:36 ` Ojaswin Mujoo
2026-04-20 23:59 ` Dave Chinner
2026-04-21 3:19 ` Fengnan
2026-04-21 22:36 ` Dave Chinner [this message]
2026-04-22 2:43 ` Fengnan
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