From: Khalid Aziz <khalid.aziz@oracle.com>
To: Mike Kravetz <mike.kravetz@oracle.com>,
David Rientjes <rientjes@google.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Song Liu <songliubraving@fb.com>,
"Kirill A.Shutemov" <kirill.shutemov@linux.intel.com>,
Mel Gorman <mgorman@techsingularity.net>,
Vlastimil Babka <vbabka@suse.cz>,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH] mm: always consider THP when adjusting min_free_kbytes
Date: Tue, 04 Feb 2020 16:37:30 -0700 [thread overview]
Message-ID: <787a40adec270a7c72ab1862f4fe1ada088818f1.camel@oracle.com> (raw)
In-Reply-To: <8cc18928-0b52-7c2e-fbc6-5952eb9b06ab@oracle.com>
On Tue, 2020-02-04 at 13:42 -0800, Mike Kravetz wrote:
> On 2/4/20 12:33 PM, David Rientjes wrote:
> >
> > So it looks like this is fixing an obvious correctness issue but
> > also now
> > requires users to rewrite the sysctl if they want to decrease the
> > min
> > watermark.
>
> Moving the call to khugepaged_adjust_min_free_kbytes as described
> above
> would avoid the THP adjustment unless we were going to overwrite the
> user defined value. Now, I am not sure overwriting the user defined
> value
> as is done today is actually the correct thing to do.
>
> Thoughts?
> Perhaps we should never overwrite a user defined value?
We might need to override user defined value if it is too low but
overriding it silently is not quite right. We should print a warning
at least. On the other hand, a user setting min_free_kbytes should know
what they are doing and if they set it too low, they have been warned
in the sysctl documentation. I would say we never override user defined
value but print a warning if the value is too low and kernel would have
adjusted it if it were not for the user defined value.
--
Khalid
prev parent reply other threads:[~2020-02-04 23:37 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-04 19:41 [PATCH] mm: always consider THP when adjusting min_free_kbytes Mike Kravetz
2020-02-04 20:33 ` David Rientjes
2020-02-04 21:42 ` Mike Kravetz
2020-02-04 21:53 ` Matthew Wilcox
2020-02-05 0:33 ` Mike Kravetz
2020-02-06 1:36 ` Mike Kravetz
2020-02-06 20:09 ` Khalid Aziz
2020-02-06 20:39 ` Matthew Wilcox
2020-02-06 21:23 ` Mike Kravetz
2020-02-06 21:32 ` Matthew Wilcox
2020-02-10 18:58 ` Mike Kravetz
2020-02-04 23:37 ` Khalid Aziz [this message]
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