From: Lance Yang <ioworker0@gmail.com>
To: Michal Hocko <mhocko@suse.com>
Cc: akpm@linux-foundation.org, zokeefe@google.com, david@redhat.com,
songmuchun@bytedance.com, shy828301@gmail.com,
peterx@redhat.com, minchan@kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/1] mm/khugepaged: bypassing unnecessary scans with MMF_DISABLE_THP check
Date: Tue, 30 Jan 2024 10:12:19 +0800 [thread overview]
Message-ID: <CAK1f24miiADZCpugOa4QUmerG70kOsMT97Zvmy=5ifOG4mW=+g@mail.gmail.com> (raw)
In-Reply-To: <ZbfSP6xt6JAE2NrH@tiehlicka>
Hey Michal,
Thanks for taking time to review!
On some servers within our company, we deploy a
daemon responsible for monitoring and updating
local applications. Some applications prefer not to
use THP, so the daemon calls prctl to disable THP
before fork/exec. Conversely, for other applications,
the daemon calls prctl to enable THP before fork/exec.
Ideally, the daemon should invoke prctl after the fork,
but its current implementation follows the described
approach.
BR,
Lance
On Tue, Jan 30, 2024 at 12:28 AM Michal Hocko <mhocko@suse.com> wrote:
>
> On Mon 29-01-24 13:45:51, Lance Yang wrote:
> > khugepaged scans the entire address space in the
> > background for each given mm, looking for
> > opportunities to merge sequences of basic pages
> > into huge pages. However, when an mm is inserted
> > to the mm_slots list, and the MMF_DISABLE_THP flag
> > is set later, this scanning process becomes
> > unnecessary for that mm and can be skipped to avoid
> > redundant operations, especially in scenarios with
> > a large address space.
>
> Is this a real problem? I thought that the prctl is called
> on the parent before fork/exec. Or are you aware of any
> applications which do call prctl late enough that the race
> would be actually observable?
> --
> Michal Hocko
> SUSE Labs
next prev parent reply other threads:[~2024-01-30 2:12 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-29 5:45 [PATCH 1/1] mm/khugepaged: bypassing unnecessary scans with MMF_DISABLE_THP check Lance Yang
2024-01-29 16:28 ` Michal Hocko
2024-01-30 2:12 ` Lance Yang [this message]
2024-01-30 3:08 ` Lance Yang
2024-01-30 9:35 ` Michal Hocko
2024-01-30 9:46 ` Lance Yang
2024-01-31 0:37 ` Lance Yang
2024-01-29 18:53 ` Yang Shi
2024-01-29 19:03 ` Zach O'Keefe
2024-01-30 2:37 ` Lance Yang
2024-01-30 2:21 ` Lance Yang
2024-01-31 9:30 ` Lance Yang
2024-01-31 20:06 ` Yang Shi
2024-02-01 1:13 ` Lance Yang
2024-02-01 18:56 ` Yang Shi
2024-02-03 3:20 ` Lance Yang
2024-02-21 22:11 ` Andrew Morton
2024-02-22 7:43 ` Lance Yang
2024-02-22 7:51 ` Lance Yang
2024-02-22 8:51 ` David Hildenbrand
2024-02-22 9:12 ` Lance Yang
2024-02-22 20:23 ` Yang Shi
2024-02-22 21:11 ` Andrew Morton
2024-02-23 7:59 ` Lance Yang
2024-02-24 1:47 ` Yang Shi
2024-02-24 1:46 ` Yang Shi
2024-02-24 3:54 ` Lance Yang
2024-02-25 4:56 ` Lance Yang
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