From: Dave Chinner <david@fromorbit.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: linux-xfs@vger.kernel.org
Subject: Re: [PATCH 1/2] xfs: separate read-only variables in struct xfs_mount
Date: Tue, 12 May 2020 19:11:43 +1000 [thread overview]
Message-ID: <20200512091143.GR2040@dread.disaster.area> (raw)
In-Reply-To: <20200512081423.GA7689@infradead.org>
On Tue, May 12, 2020 at 01:14:23AM -0700, Christoph Hellwig wrote:
> I'm surprised the difference is that big. The moves look obviously
> fine, but why do you put the precalculated fields in the middle
> of struct xfs_mount instead of at the end?
Just because it was the minimum to move about and it clearly
demonstrated the damage the contended cacheline was doing to
performance of code accessing read-only variables.
Really, there's a lot in the xfs_mount that might well be read only
that I didn't consider. I'm thinking that most of the pointers to
structures are read only (e.g. the log, ailp, buftargs, etc) as they
do not change for the life of the structure. I don't really have the
time to dig into this real deep (this is a quick, interesting
diversion!) so I did the 99-percenter and moved on...
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
next prev parent reply other threads:[~2020-05-12 9:11 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-12 2:59 [PATCH 0/2] xfs: fix a couple of performance issues Dave Chinner
2020-05-12 2:59 ` [PATCH 1/2] xfs: separate read-only variables in struct xfs_mount Dave Chinner
2020-05-12 8:14 ` Christoph Hellwig
2020-05-12 9:11 ` Dave Chinner [this message]
2020-05-12 2:59 ` [PATCH 2/2] xfs: convert m_active_trans counter to per-cpu Dave Chinner
2020-05-12 8:16 ` Christoph Hellwig
2020-05-12 9:06 ` Dave Chinner
2020-05-12 16:03 ` Darrick J. Wong
2020-05-12 21:39 ` Dave Chinner
2020-05-12 22:59 ` Darrick J. Wong
2020-05-13 17:17 ` Darrick J. Wong
-- strict thread matches above, loose matches on Subject: below --
2020-05-19 22:23 [PATCH 0/2 v3] xfs: improve transaction rate scalability Dave Chinner
2020-05-19 22:23 ` [PATCH 1/2] xfs: separate read-only variables in struct xfs_mount Dave Chinner
2020-05-20 6:57 ` Christoph Hellwig
2020-05-20 7:12 ` Dave Chinner
2020-05-20 9:43 ` Chaitanya Kulkarni
2020-05-20 20:44 ` Darrick J. Wong
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=20200512091143.GR2040@dread.disaster.area \
--to=david@fromorbit.com \
--cc=hch@infradead.org \
--cc=linux-xfs@vger.kernel.org \
/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
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.