From: Joonsoo Kim <js1304@gmail.com>
To: David Rientjes <rientjes@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Mel Gorman <mgorman@suse.de>, Rik van Riel <riel@redhat.com>,
Vlastimil Babka <vbabka@suse.cz>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Greg Thelen <gthelen@google.com>, Hugh Dickins <hughd@google.com>,
LKML <linux-kernel@vger.kernel.org>,
Linux Memory Management List <linux-mm@kvack.org>
Subject: Re: [patch] mm, thp: do not perform sync compaction on pagefault
Date: Thu, 1 May 2014 15:39:12 +0900 [thread overview]
Message-ID: <CAAmzW4Nj04rbdoe8dkA-r14j+5iStUxFLM5BEkTmgEB+tHtsUA@mail.gmail.com> (raw)
In-Reply-To: <alpine.DEB.2.02.1404301744580.8415@chino.kir.corp.google.com>
2014-05-01 9:45 GMT+09:00 David Rientjes <rientjes@google.com>:
> Synchronous memory compaction can be very expensive: it can iterate an enormous
> amount of memory without aborting and it can wait on page locks and writeback to
> complete if a pageblock cannot be defragmented.
> Unfortunately, it's too expensive for pagefault for transparent hugepages and
> it's much better to simply fallback to pages. On 128GB machines, we find that
> synchronous memory compaction can take O(seconds) for a single thp fault.
Hello,
AFAIK, synchronous compaction doesn't wait the page on writeback.
sync compaction pass MIGRATE_SYNC_LIGHT for migrate_mode,
instead of MIGRATE_SYNC. It results in skipping the page on writeback.
Thanks.
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prev parent reply other threads:[~2014-05-01 6:39 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-01 0:45 David Rientjes
2014-05-01 6:39 ` Joonsoo Kim [this message]
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