From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Nicholas Mc Guire <der.herr@hofr.at>
Cc: linux-rt-users@vger.kernel.org,
LKML <linux-kernel@vger.kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
Peter Zijlstra <peterz@infradead.org>,
Carsten Emde <C.Emde@osadl.org>,
Thomas Gleixner <tglx@linutronix.de>,
Andreas Platschek <platschek@ict.tuwien.ac.at>
Subject: Re: [PATCH RT 4/5] allow preemption in mem_cgroup_move_account_page_stat
Date: Fri, 14 Feb 2014 14:17:05 +0100 [thread overview]
Message-ID: <20140214131705.GF28438@linutronix.de> (raw)
In-Reply-To: <20140210153933.GE20017@opentech.at>
* Nicholas Mc Guire | 2014-02-10 16:39:33 [+0100]:
>index a67e630f..e7cc35a 100644
>--- a/mm/memcontrol.c
>+++ b/mm/memcontrol.c
>@@ -3784,10 +3784,10 @@ void mem_cgroup_move_account_page_stat(struct mem_cgroup *from,
> enum mem_cgroup_stat_index idx)
> {
> /* Update stat data for mem_cgroup */
>- preempt_disable();
>+ migrate_disable();
> __this_cpu_sub(from->stat->count[idx], nr_pages);
> __this_cpu_add(to->stat->count[idx], nr_pages);
>- preempt_enable();
>+ migrate_enable();
> }
Now, that I look at it again. Isn't it more efficient to keep preemption
disabled for this very short time instead instead of invoking
migrate_disable() which includes preempt_disable()/enable() and a few
more opcodes…
Therefore, I drop it again.
Sebastian
next prev parent reply other threads:[~2014-02-14 13:17 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-02-10 15:39 [PATCH RT 4/5] allow preemption in mem_cgroup_move_account_page_stat Nicholas Mc Guire
2014-02-14 13:09 ` Sebastian Andrzej Siewior
2014-02-14 13:17 ` Sebastian Andrzej Siewior [this message]
2014-02-14 13:19 ` Sebastian Andrzej Siewior
2014-02-14 15:30 ` Nicholas Mc Guire
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=20140214131705.GF28438@linutronix.de \
--to=bigeasy@linutronix.de \
--cc=C.Emde@osadl.org \
--cc=der.herr@hofr.at \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-rt-users@vger.kernel.org \
--cc=peterz@infradead.org \
--cc=platschek@ict.tuwien.ac.at \
--cc=rostedt@goodmis.org \
--cc=tglx@linutronix.de \
/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).