From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: David Rientjes <rientjes@google.com>
Cc: Michal Hocko <mhocko@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Jonathan Corbet <corbet@lwn.net>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Vlastimil Babka <vbabka@suse.cz>,
Mel Gorman <mgorman@techsingularity.net>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [patch] mm, thp: always direct reclaim for MADV_HUGEPAGE even when deferred
Date: Tue, 27 Dec 2016 05:32:08 +0300 [thread overview]
Message-ID: <20161227023208.GB8780@node.shutemov.name> (raw)
In-Reply-To: <alpine.DEB.2.10.1612261639550.99744@chino.kir.corp.google.com>
On Mon, Dec 26, 2016 at 04:53:39PM -0800, David Rientjes wrote:
> > If there is really a need for an immediate solution^Wworkaround then I
> > think that tweaking the madvise option should be reasonably safe. Admins
> > are really prepared for stalls because they are explicitly opting in for
> > madvise behavior and they will get a background compaction on top. This
> > is a new behavior but I do not see how it would be harmful. If an
> > excessive compaction is a problem then THP can be reduced to madvise
> > only vmas.
> >
> > But, I really _do_ care about having a stall free option which is not a
> > complete disable of the background compaction for THP.
> >
>
> This is completely wrong. Before the "defer" option has been introduced,
> we had "madvise" and should maintain its behavior as much as possible so
> there are no surprises. We don't change behavior for a tunable out from
> under existing users because you think you know better. With the new
> "defer" option, we can make this a stronger variant of "madvise", which
> Kirill acked, so that existing users of MADV_HUGEPAGE have no change in
> behavior and we can configure whether we do direct or background
> compaction for everybody else. If people don't want background
> compaction, they can set defrag to "madvise". If they want it, they can
> set it to "defer". It's very simple.
>
> That said, I simply don't have the time to continue in circular arguments
> and would respectfully ask Andrew to apply this acked patch.
+1.
I don't see a point to make "defer" weaker than "madvise". MADV_HUGEPAGE
is a way for an application to say that it's okay with paying price for
huge page allocation.
--
Kirill A. Shutemov
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WARNING: multiple messages have this Message-ID (diff)
From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: David Rientjes <rientjes@google.com>
Cc: Michal Hocko <mhocko@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Jonathan Corbet <corbet@lwn.net>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Vlastimil Babka <vbabka@suse.cz>,
Mel Gorman <mgorman@techsingularity.net>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [patch] mm, thp: always direct reclaim for MADV_HUGEPAGE even when deferred
Date: Tue, 27 Dec 2016 05:32:08 +0300 [thread overview]
Message-ID: <20161227023208.GB8780@node.shutemov.name> (raw)
In-Reply-To: <alpine.DEB.2.10.1612261639550.99744@chino.kir.corp.google.com>
On Mon, Dec 26, 2016 at 04:53:39PM -0800, David Rientjes wrote:
> > If there is really a need for an immediate solution^Wworkaround then I
> > think that tweaking the madvise option should be reasonably safe. Admins
> > are really prepared for stalls because they are explicitly opting in for
> > madvise behavior and they will get a background compaction on top. This
> > is a new behavior but I do not see how it would be harmful. If an
> > excessive compaction is a problem then THP can be reduced to madvise
> > only vmas.
> >
> > But, I really _do_ care about having a stall free option which is not a
> > complete disable of the background compaction for THP.
> >
>
> This is completely wrong. Before the "defer" option has been introduced,
> we had "madvise" and should maintain its behavior as much as possible so
> there are no surprises. We don't change behavior for a tunable out from
> under existing users because you think you know better. With the new
> "defer" option, we can make this a stronger variant of "madvise", which
> Kirill acked, so that existing users of MADV_HUGEPAGE have no change in
> behavior and we can configure whether we do direct or background
> compaction for everybody else. If people don't want background
> compaction, they can set defrag to "madvise". If they want it, they can
> set it to "defer". It's very simple.
>
> That said, I simply don't have the time to continue in circular arguments
> and would respectfully ask Andrew to apply this acked patch.
+1.
I don't see a point to make "defer" weaker than "madvise". MADV_HUGEPAGE
is a way for an application to say that it's okay with paying price for
huge page allocation.
--
Kirill A. Shutemov
next prev parent reply other threads:[~2016-12-27 2:32 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-22 0:21 [patch] mm, thp: always direct reclaim for MADV_HUGEPAGE even when deferred David Rientjes
2016-12-22 0:21 ` David Rientjes
2016-12-22 8:31 ` Kirill A. Shutemov
2016-12-22 8:31 ` Kirill A. Shutemov
2016-12-22 10:00 ` Michal Hocko
2016-12-22 10:00 ` Michal Hocko
2016-12-22 21:05 ` David Rientjes
2016-12-22 21:05 ` David Rientjes
2016-12-23 8:51 ` Michal Hocko
2016-12-23 8:51 ` Michal Hocko
2016-12-23 10:01 ` David Rientjes
2016-12-23 10:01 ` David Rientjes
2016-12-23 11:18 ` Michal Hocko
2016-12-23 11:18 ` Michal Hocko
2016-12-23 22:46 ` David Rientjes
2016-12-23 22:46 ` David Rientjes
2016-12-26 9:02 ` Michal Hocko
2016-12-26 9:02 ` Michal Hocko
2016-12-27 0:53 ` David Rientjes
2016-12-27 0:53 ` David Rientjes
2016-12-27 2:32 ` Kirill A. Shutemov [this message]
2016-12-27 2:32 ` Kirill A. Shutemov
2016-12-27 9:41 ` Michal Hocko
2016-12-27 9:41 ` Michal Hocko
2016-12-27 21:36 ` David Rientjes
2016-12-27 21:36 ` David Rientjes
2016-12-28 8:48 ` Michal Hocko
2016-12-28 8:48 ` Michal Hocko
2016-12-28 21:33 ` David Rientjes
2016-12-28 21:33 ` David Rientjes
2016-12-29 8:24 ` Michal Hocko
2016-12-29 8:24 ` Michal Hocko
2016-12-30 12:36 ` Mel Gorman
2016-12-30 12:36 ` Mel Gorman
2016-12-30 12:56 ` Michal Hocko
2016-12-30 12:56 ` Michal Hocko
2016-12-30 14:08 ` Mel Gorman
2016-12-30 14:08 ` Mel Gorman
2016-12-30 22:30 ` David Rientjes
2016-12-30 22:30 ` David Rientjes
2017-01-03 10:37 ` Mel Gorman
2017-01-03 10:37 ` Mel Gorman
2017-01-03 21:57 ` David Rientjes
2017-01-03 21:57 ` David Rientjes
2017-01-04 10:12 ` Mel Gorman
2017-01-04 10:12 ` Mel Gorman
2017-01-04 21:53 ` David Rientjes
2017-01-04 21:53 ` David Rientjes
2017-01-02 8:38 ` Vlastimil Babka
2017-01-02 8:38 ` Vlastimil Babka
2017-01-03 22:44 ` David Rientjes
2017-01-03 22:44 ` David Rientjes
2017-01-04 8:32 ` Vlastimil Babka
2017-01-04 8:32 ` Vlastimil Babka
2017-01-04 9:46 ` Michal Hocko
2017-01-04 9:46 ` Michal Hocko
2017-01-04 22:04 ` David Rientjes
2017-01-04 22:04 ` David Rientjes
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