From: Joonsoo Kim <iamjoonsoo.kim@lge.com>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrew Morton <akpm@linux-foundation.org>,
David Rientjes <rientjes@google.com>,
linux-kernel@vger.kernel.org, linux-mm@vger.kernel.org,
Minchan Kim <minchan@kernel.org>,
Michal Nazarewicz <mina86@mina86.com>,
Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
Christoph Lameter <cl@linux.com>, Rik van Riel <riel@redhat.com>,
Mel Gorman <mgorman@suse.de>,
Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Subject: Re: [PATCH v5 07/14] mm, compaction: khugepaged should not give up due to need_resched()
Date: Tue, 29 Jul 2014 15:53:27 +0900 [thread overview]
Message-ID: <20140729065327.GB1610@js1304-P5Q-DELUXE> (raw)
In-Reply-To: <1406553101-29326-8-git-send-email-vbabka@suse.cz>
On Mon, Jul 28, 2014 at 03:11:34PM +0200, Vlastimil Babka wrote:
> Async compaction aborts when it detects zone lock contention or need_resched()
> is true. David Rientjes has reported that in practice, most direct async
> compactions for THP allocation abort due to need_resched(). This means that a
> second direct compaction is never attempted, which might be OK for a page
> fault, but khugepaged is intended to attempt a sync compaction in such case and
> in these cases it won't.
I have a silly question here.
Why need_resched() is criteria to stop async compaction?
need_resched() is flagged up when time slice runs out or other reasons.
It means that we should stop async compaction at arbitrary timing
because process can be on compaction code at arbitrary moment. I think
that it isn't reasonable and it doesn't ensure anything. Instead of
this approach, how about doing compaction on certain amounts of pageblock
for async compaction?
Thanks.
next prev parent reply other threads:[~2014-07-29 6:46 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-07-28 13:11 [PATCH v5 00/14] compaction: balancing overhead and success rates Vlastimil Babka
2014-07-28 13:11 ` [PATCH v5 01/14] mm, THP: don't hold mmap_sem in khugepaged when allocating THP Vlastimil Babka
2014-07-28 23:39 ` David Rientjes
2014-07-28 13:11 ` [PATCH v5 02/14] mm, compaction: defer each zone individually instead of preferred zone Vlastimil Babka
2014-07-28 23:59 ` David Rientjes
2014-07-29 9:02 ` Vlastimil Babka
2014-07-29 6:38 ` Joonsoo Kim
2014-07-29 9:12 ` Vlastimil Babka
2014-07-30 16:22 ` Vlastimil Babka
2014-08-01 8:51 ` Vlastimil Babka
2014-08-04 6:45 ` Joonsoo Kim
2014-07-28 13:11 ` [PATCH v5 03/14] mm, compaction: do not count compact_stall if all zones skipped compaction Vlastimil Babka
2014-07-29 0:04 ` David Rientjes
2014-07-28 13:11 ` [PATCH v5 04/14] mm, compaction: do not recheck suitable_migration_target under lock Vlastimil Babka
2014-07-28 13:11 ` [PATCH v5 05/14] mm, compaction: move pageblock checks up from isolate_migratepages_range() Vlastimil Babka
2014-07-29 0:29 ` David Rientjes
2014-07-29 9:27 ` Vlastimil Babka
2014-07-29 23:02 ` David Rientjes
2014-07-29 23:21 ` Kirill A. Shutemov
2014-07-29 23:51 ` David Rientjes
2014-07-30 9:27 ` Vlastimil Babka
2014-07-30 9:39 ` Vlastimil Babka
2014-07-28 13:11 ` [PATCH v5 06/14] mm, compaction: reduce zone checking frequency in the migration scanner Vlastimil Babka
2014-07-29 0:44 ` David Rientjes
2014-07-29 9:31 ` Vlastimil Babka
2014-07-28 13:11 ` [PATCH v5 07/14] mm, compaction: khugepaged should not give up due to need_resched() Vlastimil Babka
2014-07-29 0:59 ` David Rientjes
2014-07-29 9:45 ` Vlastimil Babka
2014-07-29 22:57 ` David Rientjes
2014-07-29 6:53 ` Joonsoo Kim [this message]
2014-07-29 7:31 ` David Rientjes
2014-07-29 8:27 ` Joonsoo Kim
2014-07-29 9:16 ` David Rientjes
2014-07-29 9:49 ` Vlastimil Babka
2014-07-29 22:53 ` David Rientjes
2014-07-30 9:08 ` Vlastimil Babka
2014-07-28 13:11 ` [PATCH v5 08/14] mm, compaction: periodically drop lock and restore IRQs in scanners Vlastimil Babka
2014-07-29 1:03 ` David Rientjes
2014-07-28 13:11 ` [PATCH v5 09/14] mm, compaction: skip rechecks when lock was already held Vlastimil Babka
2014-07-28 13:11 ` [PATCH v5 10/14] mm, compaction: remember position within pageblock in free pages scanner Vlastimil Babka
2014-07-28 13:11 ` [PATCH v5 11/14] mm, compaction: skip buddy pages by their order in the migrate scanner Vlastimil Babka
2014-07-29 1:05 ` David Rientjes
2014-07-28 13:11 ` [PATCH v5 12/14] mm: rename allocflags_to_migratetype for clarity Vlastimil Babka
2014-07-28 13:11 ` [PATCH v5 13/14] mm, compaction: pass gfp mask to compact_control Vlastimil Babka
2014-07-28 13:11 ` [PATCH v5 14/14] mm, compaction: try to capture the just-created high-order freepage Vlastimil Babka
2014-07-29 7:34 ` Joonsoo Kim
2014-07-29 15:34 ` Vlastimil Babka
2014-07-30 8:39 ` Joonsoo Kim
2014-07-30 9:56 ` Vlastimil Babka
2014-07-30 14:19 ` Joonsoo Kim
2014-07-30 15:05 ` Vlastimil Babka
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