From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
To: Vijay Balakrishna <vijayb@linux.microsoft.com>
Cc: Michal Hocko <mhocko@suse.com>,
Andrew Morton <akpm@linux-foundation.org>,
Oleg Nesterov <oleg@redhat.com>, Song Liu <songliubraving@fb.com>,
Andrea Arcangeli <aarcange@redhat.com>,
Pavel Tatashin <pasha.tatashin@soleen.com>,
Allen Pais <apais@microsoft.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [v4] mm: khugepaged: avoid overriding min_free_kbytes set by user
Date: Tue, 22 Sep 2020 10:07:26 +0300 [thread overview]
Message-ID: <20200922070726.dlw24lf3wd3p2ias@black.fi.intel.com> (raw)
In-Reply-To: <e4eb32bb-f905-d15b-8596-13bf387b9f57@linux.microsoft.com>
On Mon, Sep 21, 2020 at 12:07:23PM -0700, Vijay Balakrishna wrote:
> >
> > I would recommend reposting the patch which adds heuristic for THP (if
> > THP is enabled) into the hotplug path, arguing with the consistency and
> > surprising results when adding memory decreases the value.
>
> I hope my reposted patch
> ([v3 1/2] mm: khugepaged: recalculate min_free_kbytes after memory hotplug
> as expected by khugepaged)
> change log is ok:
>
> When memory is hotplug added or removed the min_free_kbytes must be
> recalculated based on what is expected by khugepaged. Currently
> after hotplug, min_free_kbytes will be set to a lower default and higher
> default set when THP enabled is lost. This change restores min_free_kbytes
> as expected for THP consumers.
Any scenario when hotremove would result in changing min_free_kbytes?
> > Your initial
> > problem is in sizing as mentioned in other email thread and you should
> > be investigating more but this inconsistency might really come as a
> > surprise.
> >
> > All that if Kirill is reconsidering his initial position of course.
> >
>
> Kirill, can you comment or share your opinion?
Looking again, never decreasing min_free_kbytes is the most reasonable
policy. Sorry for the noise.
But I would like to see a scenario when hotremov will end up changing
min_free_kbytes. It's not obvious to me.
--
Kirill A. Shutemov
next prev parent reply other threads:[~2020-09-22 7:07 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-17 6:39 [v4] mm: khugepaged: avoid overriding min_free_kbytes set by user Vijay Balakrishna
2020-09-17 9:28 ` Michal Hocko
2020-09-17 9:34 ` Michal Hocko
2020-09-17 17:27 ` Vijay Balakrishna
2020-09-17 17:52 ` Michal Hocko
2020-09-17 18:16 ` Vijay Balakrishna
2020-09-18 5:56 ` Michal Hocko
2020-09-21 19:07 ` Vijay Balakrishna
2020-09-22 7:07 ` Kirill A. Shutemov [this message]
2020-09-22 10:07 ` Michal Hocko
2020-09-22 16:10 ` Vijay Balakrishna
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