From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>, Miao Xie <miaox@cn.fujitsu.com>,
David Rientjes <rientjes@google.com>,
Christoph Lameter <cl@linux.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Pekka Enberg <penberg@cs.helsinki.fi>
Subject: Re: [PATCH] mm: Optimize put_mems_allowed() usage
Date: Thu, 17 May 2012 22:23:24 +0200 [thread overview]
Message-ID: <1337286204.4281.87.camel@twins> (raw)
In-Reply-To: <20120517131610.d1b09fd8.akpm@linux-foundation.org>
On Thu, 2012-05-17 at 13:16 -0700, Andrew Morton wrote:
> I do think it was a bad idea to remove that comment. As it stands, the
> reader will be wondering why we did the read_mems_allowed_begin() at
> all, and whether failing to check for a change is a bug.
>
> --- a/mm/slub.c~mm-optimize-put_mems_allowed-usage-fix
> +++ a/mm/slub.c
> @@ -1624,8 +1624,16 @@ static struct page *get_any_partial(stru
> if (n && cpuset_zone_allowed_hardwall(zone, flags) &&
> n->nr_partial > s->min_partial) {
> object = get_partial_node(s, n, c);
> - if (object)
> + if (object) {
> + /*
> + * Don't check read_mems_allowed_retry()
> + * here - if mems_allowed was updated in
> + * parallel, that was a harmless race
> + * between allocation and the cpuset
> + * update
> + */
> return object;
> + }
> }
> }
> } while (read_mems_allowed_retry(cpuset_mems_cookie));
OK, it seemed weird to have that comment in this one place whilst it is
the general pattern of this construct.
The whole read_mems_allowed_retry() should only ever be attempted in
case the allocation failed.
But sure..
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2012-05-17 20:23 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-03-07 18:08 [PATCH] cpuset: mm: Reduce large amounts of memory barrier related damage v3 Mel Gorman
2012-03-26 10:56 ` Peter Zijlstra
2012-03-26 11:07 ` Peter Zijlstra
2012-03-26 15:50 ` Mel Gorman
2012-03-26 16:20 ` Peter Zijlstra
2012-03-27 12:47 ` Mel Gorman
2012-03-27 13:14 ` [PATCH] mm: Optimize put_mems_allowed() usage Peter Zijlstra
2012-05-17 10:33 ` Peter Zijlstra
2012-05-17 20:16 ` Andrew Morton
2012-05-17 20:23 ` Peter Zijlstra [this message]
2013-08-23 13:03 ` [PATCH] cpuset: mm: Reduce large amounts of memory barrier related damage v3 Peter Zijlstra
2013-08-23 18:15 ` Peter Zijlstra
2013-08-26 5:32 ` Rik van Riel
2013-08-29 9:28 ` Mel Gorman
2013-08-29 9:43 ` Peter Zijlstra
2013-08-29 9:45 ` Peter Zijlstra
2013-08-29 10:56 ` Mel Gorman
2013-08-29 11:14 ` Peter Zijlstra
2013-08-29 12:10 ` Mel Gorman
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=1337286204.4281.87.camel@twins \
--to=a.p.zijlstra@chello.nl \
--cc=akpm@linux-foundation.org \
--cc=cl@linux.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mgorman@suse.de \
--cc=miaox@cn.fujitsu.com \
--cc=penberg@cs.helsinki.fi \
--cc=rientjes@google.com \
/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 NNTP newsgroup(s).