From: Rafael Aquini <aquini@redhat.com>
To: Mel Gorman <mgorman@suse.de>
Cc: Richard Davies <richard@arachsys.com>, KVM <kvm@vger.kernel.org>,
QEMU-devel <qemu-devel@nongnu.org>,
LKML <linux-kernel@vger.kernel.org>,
Linux-MM <linux-mm@kvack.org>, Avi Kivity <avi@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
Shaohua Li <shli@kernel.org>
Subject: Re: [Qemu-devel] [PATCH 5/9] mm: compaction: Acquire the zone->lru_lock as late as possible
Date: Fri, 21 Sep 2012 14:51:15 -0300 [thread overview]
Message-ID: <20120921175115.GE6665@optiplex.redhat.com> (raw)
In-Reply-To: <1348224383-1499-6-git-send-email-mgorman@suse.de>
On Fri, Sep 21, 2012 at 11:46:19AM +0100, Mel Gorman wrote:
> Compactions migrate scanner acquires the zone->lru_lock when scanning a range
> of pages looking for LRU pages to acquire. It does this even if there are
> no LRU pages in the range. If multiple processes are compacting then this
> can cause severe locking contention. To make matters worse commit b2eef8c0
> (mm: compaction: minimise the time IRQs are disabled while isolating pages
> for migration) releases the lru_lock every SWAP_CLUSTER_MAX pages that are
> scanned.
>
> This patch makes two changes to how the migrate scanner acquires the LRU
> lock. First, it only releases the LRU lock every SWAP_CLUSTER_MAX pages if
> the lock is contended. This reduces the number of times it unnecessarily
> disables and re-enables IRQs. The second is that it defers acquiring the
> LRU lock for as long as possible. If there are no LRU pages or the only
> LRU pages are transhuge then the LRU lock will not be acquired at all
> which reduces contention on zone->lru_lock.
>
> Signed-off-by: Mel Gorman <mgorman@suse.de>
> Acked-by: Rik van Riel <riel@redhat.com>
> ---
Acked-by: Rafael Aquini <aquini@redhat.com>
next prev parent reply other threads:[~2012-09-21 17:51 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-21 10:46 [Qemu-devel] [PATCH 0/9] Reduce compaction scanning and lock contention Mel Gorman
2012-09-21 10:46 ` [Qemu-devel] [PATCH 1/9] Revert "mm: compaction: check lock contention first before taking lock" Mel Gorman
2012-09-21 17:46 ` Rafael Aquini
2012-09-21 10:46 ` [Qemu-devel] [PATCH 2/9] Revert "mm-compaction-abort-compaction-loop-if-lock-is-contended-or-run-too-long-fix" Mel Gorman
2012-09-21 17:47 ` Rafael Aquini
2012-09-21 10:46 ` [Qemu-devel] [PATCH 3/9] Revert "mm: compaction: abort compaction loop if lock is contended or run too long" Mel Gorman
2012-09-21 17:48 ` Rafael Aquini
2012-09-21 10:46 ` [Qemu-devel] [PATCH 4/9] mm: compaction: Abort compaction loop if lock is contended or run too long Mel Gorman
2012-09-21 17:50 ` Rafael Aquini
2012-09-21 21:31 ` Andrew Morton
2012-09-25 7:34 ` Minchan Kim
2012-09-21 10:46 ` [Qemu-devel] [PATCH 5/9] mm: compaction: Acquire the zone->lru_lock as late as possible Mel Gorman
2012-09-21 17:51 ` Rafael Aquini [this message]
2012-09-25 7:05 ` Minchan Kim
2012-09-25 7:51 ` Mel Gorman
2012-09-25 8:13 ` Minchan Kim
2012-09-25 21:39 ` Andrew Morton
2012-09-26 0:23 ` Minchan Kim
2012-09-26 10:17 ` Mel Gorman
2012-09-21 10:46 ` [Qemu-devel] [PATCH 6/9] mm: compaction: Acquire the zone->lock " Mel Gorman
2012-09-21 17:52 ` Rafael Aquini
2012-09-21 21:35 ` Andrew Morton
2012-09-24 8:52 ` Mel Gorman
2012-09-25 7:36 ` Minchan Kim
2012-09-25 7:35 ` Minchan Kim
2012-09-21 10:46 ` [Qemu-devel] [PATCH 7/9] Revert "mm: have order > 0 compaction start off where it left" Mel Gorman
2012-09-21 17:52 ` Rafael Aquini
2012-09-25 7:37 ` Minchan Kim
2012-09-21 10:46 ` [Qemu-devel] [PATCH 8/9] mm: compaction: Cache if a pageblock was scanned and no pages were isolated Mel Gorman
2012-09-21 17:53 ` Rafael Aquini
2012-09-21 21:36 ` Andrew Morton
2012-09-24 9:39 ` Mel Gorman
2012-09-24 21:26 ` Andrew Morton
2012-09-25 9:12 ` Mel Gorman
2012-09-25 20:03 ` Andrew Morton
2012-09-27 12:06 ` [Qemu-devel] [PATCH] mm: compaction: cache if a pageblock was scanned and no pages were isolated -fix2 Mel Gorman
2012-09-27 13:12 ` [Qemu-devel] [PATCH 8/9] mm: compaction: Cache if a pageblock was scanned and no pages were isolated Mel Gorman
2012-09-26 0:49 ` Minchan Kim
2012-09-27 12:14 ` Mel Gorman
2012-09-21 10:46 ` [Qemu-devel] [PATCH 9/9] mm: compaction: Restart compaction from near where it left off Mel Gorman
2012-09-21 17:54 ` Rafael Aquini
2012-09-21 13:51 ` [Qemu-devel] [PATCH 0/9] Reduce compaction scanning and lock contention Rik van Riel
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