LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Vlastimil Babka <vbabka@suse.cz>
To: Mel Gorman <mgorman@techsingularity.net>,
Andrew Morton <akpm@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@kernel.org>, Hugh Dickins <hughd@google.com>,
Linux-MM <linux-mm@kvack.org>,
Linux-RT-Users <linux-rt-users@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/1] mm/vmstat: Protect per cpu variables with preempt disable on RT
Date: Fri, 6 Aug 2021 14:38:54 +0200 [thread overview]
Message-ID: <d54e0958-5680-0d5c-e4a7-6ec4afe53b48@suse.cz> (raw)
In-Reply-To: <20210805160019.1137-2-mgorman@techsingularity.net>
On 8/5/21 6:00 PM, Mel Gorman wrote:
> From: Ingo Molnar <mingo@elte.hu>
>
> Disable preemption on -RT for the vmstat code. On vanila the code runs
> in IRQ-off regions while on -RT it may not when stats are updated under
> a local_lock. "preempt_disable" ensures that the same resources is not
> updated in parallel due to preemption.
>
> This patch differs from the preempt-rt version where __count_vm_event and
> __count_vm_events are also protected. The counters are explicitly "allowed
> to be to be racy" so there is no need to protect them from preemption. Only
> the accurate page stats that are updated by a read-modify-write need
> protection. This patch also differs in that a preempt_[en|dis]able_rt
> helper is not used. As vmstat is the only user of the helper, it was
> suggested that it be open-coded in vmstat.c instead of risking the helper
> being used in unnecessary contexts.
>
> Signed-off-by: Ingo Molnar <mingo@elte.hu>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
next prev parent reply other threads:[~2021-08-06 12:39 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-05 16:00 [PATCH 0/1 v2] Protect vmstats on PREEMPT_RT Mel Gorman
2021-08-05 16:00 ` [PATCH 1/1] mm/vmstat: Protect per cpu variables with preempt disable on RT Mel Gorman
2021-08-05 23:22 ` Andrew Morton
2021-08-06 7:50 ` Vlastimil Babka
2021-08-06 8:44 ` Mel Gorman
2021-08-06 12:38 ` Vlastimil Babka [this message]
2021-08-31 16:45 ` Sebastian Andrzej Siewior
2021-09-02 20:07 ` Andrew Morton
2021-09-06 13:48 ` Mel Gorman
2021-09-06 14:03 ` Sebastian Andrzej Siewior
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=d54e0958-5680-0d5c-e4a7-6ec4afe53b48@suse.cz \
--to=vbabka@suse.cz \
--cc=akpm@linux-foundation.org \
--cc=hughd@google.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=linux-rt-users@vger.kernel.org \
--cc=mgorman@techsingularity.net \
--cc=mingo@kernel.org \
--cc=tglx@linutronix.de \
--subject='Re: [PATCH 1/1] mm/vmstat: Protect per cpu variables with preempt disable on RT' \
/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
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).