From: Matthew Wilcox <willy@infradead.org>
To: Haifeng Xu <haifeng.xu@shopee.com>
Cc: David Hildenbrand <david@redhat.com>,
akpm@linux-foundation.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm: remove redundant check in handle_mm_fault
Date: Tue, 7 Mar 2023 02:48:53 +0000 [thread overview]
Message-ID: <ZAamFX/hq6Y/iNJb@casper.infradead.org> (raw)
In-Reply-To: <354360d5-dce6-a11c-ee61-d41e615bfa05@shopee.com>
On Tue, Mar 07, 2023 at 10:36:55AM +0800, Haifeng Xu wrote:
> On 2023/3/6 21:49, David Hildenbrand wrote:
> > On 06.03.23 03:49, Haifeng Xu wrote:
> >> mem_cgroup_oom_synchronize() has checked whether current memcg_in_oom is
> >> set or not, so remove the check in handle_mm_fault().
> >
> > "mem_cgroup_oom_synchronize() will returned immediately if memcg_in_oom is not set, so remove the check from handle_mm_fault()".
> >
> > However, that requires now always an indirect function call -- do we care about dropping that optimization?
> >
> >
>
> If memcg_in_oom is set, we will check it twice, one is from handle_mm_fault(), the other is from mem_cgroup_oom_synchronize(). That seems a bit redundant.
>
> if memcg_in_oom is not set, mem_cgroup_oom_synchronize() returns directly. Though it's an indirect function call, but the time spent can be negligible
> compare to the whole mm user falut preocess. And that won't cause stack overflow error.
I suggest you measure it.
next prev parent reply other threads:[~2023-03-07 2:49 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-06 2:49 Haifeng Xu
2023-03-06 13:49 ` David Hildenbrand
2023-03-07 2:36 ` Haifeng Xu
2023-03-07 2:48 ` Matthew Wilcox [this message]
2023-03-07 3:20 ` Haifeng Xu
2023-03-08 9:03 ` Haifeng Xu
2023-03-08 9:13 ` David Hildenbrand
2023-03-09 2:33 ` Haifeng Xu
2023-03-14 8:05 ` Haifeng Xu
2023-03-14 9:09 ` David Hildenbrand
2023-03-14 10:29 ` Haifeng Xu
2023-03-14 12:40 ` Matthew Wilcox
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