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From: Vlastimil Babka <vbabka@suse.cz>
To: Michal Hocko <mhocko@kernel.org>, linux-api@vger.kernel.org
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Alexey Dobriyan <adobriyan@gmail.com>,
	linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>,
	Michal Hocko <mhocko@suse.com>
Subject: Re: [RFC PATCH 3/3] mm, proc: report PR_SET_THP_DISABLE in proc
Date: Fri, 23 Nov 2018 16:49:04 +0100	[thread overview]
Message-ID: <d07d9742-e7dc-0fe7-c4be-3bd9a60fde98@suse.cz> (raw)
In-Reply-To: <20181120103515.25280-4-mhocko@kernel.org>

On 11/20/18 11:35 AM, Michal Hocko wrote:
> From: Michal Hocko <mhocko@suse.com>
> 
> David Rientjes has reported that 1860033237d4 ("mm: make
> PR_SET_THP_DISABLE immediately active") has changed the way how
> we report THPable VMAs to the userspace. Their monitoring tool is
> triggering false alarms on PR_SET_THP_DISABLE tasks because it considers
> an insufficient THP usage as a memory fragmentation resp. memory
> pressure issue.
> 
> Before the said commit each newly created VMA inherited VM_NOHUGEPAGE
> flag and that got exposed to the userspace via /proc/<pid>/smaps file.
> This implementation had its downsides as explained in the commit message
> but it is true that the userspace doesn't have any means to query for
> the process wide THP enabled/disabled status.
> 
> PR_SET_THP_DISABLE is a process wide flag so it makes a lot of sense
> to export in the process wide context rather than per-vma. Introduce

Agreed.

> a new field to /proc/<pid>/status which export this status.  If
> PR_SET_THP_DISABLE is used then it reports false same as when the THP is
> not compiled in. It doesn't consider the global THP status because we
> already export that information via sysfs
> 
> Fixes: 1860033237d4 ("mm: make PR_SET_THP_DISABLE immediately active")
> Signed-off-by: Michal Hocko <mhocko@suse.com>

Acked-by: Vlastimil Babka <vbabka@suse.cz>

  parent reply	other threads:[~2018-11-23 15:49 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-20 10:35 [RFC PATCH 0/3] THP eligibility reporting via proc Michal Hocko
2018-11-20 10:35 ` Michal Hocko
2018-11-20 10:35 ` [RFC PATCH 1/3] mm, proc: be more verbose about unstable VMA flags in /proc/<pid>/smaps Michal Hocko
2018-11-20 10:35   ` Michal Hocko
2018-11-20 10:51   ` Jan Kara
2018-11-20 11:41     ` Michal Hocko
2018-11-21  0:01     ` David Rientjes
2018-11-21  6:56       ` Michal Hocko
2018-11-20 18:32   ` Dan Williams
2018-11-21  7:05     ` Michal Hocko
2018-11-21 18:01       ` Mike Rapoport
2018-11-21 17:54   ` Mike Rapoport
2018-11-21 17:58     ` Michal Hocko
2018-11-23 13:47   ` Vlastimil Babka
2018-11-20 10:35 ` [RFC PATCH 2/3] mm, thp, proc: report THP eligibility for each vma Michal Hocko
2018-11-20 10:35   ` Michal Hocko
2018-11-20 11:42   ` Michal Hocko
2018-11-23 15:07   ` Vlastimil Babka
2018-11-23 15:21     ` Michal Hocko
2018-11-23 15:24       ` Vlastimil Babka
2018-11-20 10:35 ` [RFC PATCH 3/3] mm, proc: report PR_SET_THP_DISABLE in proc Michal Hocko
2018-11-20 10:35   ` Michal Hocko
2018-11-20 11:42   ` Michal Hocko
2018-11-23 15:49   ` Vlastimil Babka [this message]
2018-11-27  0:33   ` William Kucharski
2018-11-27 13:17     ` Michal Hocko
2018-11-27 14:50       ` William Kucharski
2018-11-27 16:25         ` Michal Hocko
2018-11-27 16:50         ` Vlastimil Babka
2018-11-27 17:06           ` William Kucharski
2018-12-07 10:55 ` [RFC PATCH 0/3] THP eligibility reporting via proc Michal Hocko

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