From: Al Viro <viro@zeniv.linux.org.uk>
To: Dave Chinner <david@fromorbit.com>
Cc: linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org,
linux-cachefs@redhat.com, dhowells@redhat.com,
gfs2@lists.linux.dev, dm-devel@lists.linux.dev,
linux-security-module@vger.kernel.org, selinux@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 04/11] lib/dlock-list: Make sibling CPUs share the same linked list
Date: Thu, 7 Dec 2023 06:49:18 +0000 [thread overview]
Message-ID: <20231207064918.GZ1674809@ZenIV> (raw)
In-Reply-To: <20231206060629.2827226-5-david@fromorbit.com>
On Wed, Dec 06, 2023 at 05:05:33PM +1100, Dave Chinner wrote:
> From: Waiman Long <longman@redhat.com>
>
> The dlock list needs one list for each of the CPUs available. However,
> for sibling CPUs, they are sharing the L2 and probably L1 caches
> too. As a result, there is not much to gain in term of avoiding
> cacheline contention while increasing the cacheline footprint of the
> L1/L2 caches as separate lists may need to be in the cache.
>
> This patch makes all the sibling CPUs share the same list, thus
> reducing the number of lists that need to be maintained in each
> dlock list without having any noticeable impact on performance. It
> also improves dlock list iteration performance as fewer lists need
> to be iterated.
Probably a dumb question, but... "available" != "possible"; the code
actually goes for the latter, which avoids nasty questions about
CPU hotplug interations. Is the sibling relation on CPUs unchanging
on CPU hotplug?
next prev parent reply other threads:[~2023-12-07 6:49 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-12-06 6:05 [PATCH 0/11] vfs: inode cache scalability improvements Dave Chinner
2023-12-06 6:05 ` [PATCH 01/11] lib/dlock-list: Distributed and lock-protected lists Dave Chinner
2023-12-07 2:23 ` Al Viro
2023-12-06 6:05 ` [PATCH 02/11] vfs: Remove unnecessary list_for_each_entry_safe() variants Dave Chinner
2023-12-07 2:26 ` Al Viro
2023-12-07 4:18 ` Kent Overstreet
2023-12-06 6:05 ` [PATCH 03/11] vfs: Use dlock list for superblock's inode list Dave Chinner
2023-12-07 2:40 ` Al Viro
2023-12-07 4:59 ` Dave Chinner
2023-12-07 5:03 ` Kent Overstreet
2023-12-06 6:05 ` [PATCH 04/11] lib/dlock-list: Make sibling CPUs share the same linked list Dave Chinner
2023-12-07 4:31 ` Kent Overstreet
2023-12-07 5:42 ` Kent Overstreet
2023-12-07 6:25 ` Dave Chinner
2023-12-07 6:49 ` Al Viro [this message]
2023-12-06 6:05 ` [PATCH 05/11] selinux: use dlist for isec inode list Dave Chinner
2023-12-06 21:52 ` Paul Moore
2023-12-06 23:04 ` Dave Chinner
2023-12-07 0:36 ` Paul Moore
2023-12-06 6:05 ` [PATCH 06/11] vfs: factor out inode hash head calculation Dave Chinner
2023-12-07 3:02 ` Al Viro
2023-12-06 6:05 ` [PATCH 07/11] hlist-bl: add hlist_bl_fake() Dave Chinner
2023-12-07 3:05 ` Al Viro
2023-12-06 6:05 ` [PATCH 08/11] vfs: inode cache conversion to hash-bl Dave Chinner
2023-12-07 4:58 ` Kent Overstreet
2023-12-07 6:03 ` Dave Chinner
2023-12-07 6:42 ` Al Viro
2023-12-06 6:05 ` [PATCH 09/11] hash-bl: explicitly initialise hash-bl heads Dave Chinner
2023-12-07 3:15 ` Al Viro
2023-12-06 6:05 ` [PATCH 10/11] list_bl: don't use bit locks for PREEMPT_RT or lockdep Dave Chinner
2023-12-07 4:16 ` Kent Overstreet
2023-12-07 4:41 ` Dave Chinner
2023-12-06 6:05 ` [PATCH 11/11] hlist-bl: introduced nested locking for dm-snap Dave Chinner
2023-12-07 17:08 ` [PATCH 0/11] vfs: inode cache scalability improvements Kent Overstreet
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=20231207064918.GZ1674809@ZenIV \
--to=viro@zeniv.linux.org.uk \
--cc=david@fromorbit.com \
--cc=dhowells@redhat.com \
--cc=dm-devel@lists.linux.dev \
--cc=gfs2@lists.linux.dev \
--cc=linux-block@vger.kernel.org \
--cc=linux-cachefs@redhat.com \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-security-module@vger.kernel.org \
--cc=selinux@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 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 read-only IMAP folder(s) and NNTP newsgroup(s).