From: Mel Gorman <mgorman@suse.de>
To: David Rientjes <rientjes@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Rik van Riel <riel@redhat.com>, Minchan Kim <minchan@kernel.org>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [patch] mm, compaction: periodically schedule when freeing pages
Date: Tue, 10 Sep 2013 14:20:32 +0100 [thread overview]
Message-ID: <20130910132032.GO22421@suse.de> (raw)
In-Reply-To: <alpine.DEB.2.02.1309041625060.29607@chino.kir.corp.google.com>
On Wed, Sep 04, 2013 at 04:25:59PM -0700, David Rientjes wrote:
> We've been getting warnings about an excessive amount of time spent
> allocating pages for migration during memory compaction without
> scheduling. isolate_freepages_block() already periodically checks for
> contended locks or the need to schedule, but isolate_freepages() never
> does.
>
> When a zone is massively long and no suitable targets can be found, this
> iteration can be quite expensive without ever doing cond_resched().
>
> Check periodically for the need to reschedule while the compaction free
> scanner iterates.
>
> Signed-off-by: David Rientjes <rientjes@google.com>
Ok, fair enough.
Acked-by: Mel Gorman <mgorman@suse.de>
However I'm curious. Do you know why the combined use of
compact_cached_free_pfn and pageblock skip bits is not enough for the scanner
to quickly find a pageblock that is suitable for isolate_freepages_block()?
Is the pageblock skip information getting cleared frequently by kswapd
or something?
--
Mel Gorman
SUSE Labs
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WARNING: multiple messages have this Message-ID (diff)
From: Mel Gorman <mgorman@suse.de>
To: David Rientjes <rientjes@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Rik van Riel <riel@redhat.com>, Minchan Kim <minchan@kernel.org>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [patch] mm, compaction: periodically schedule when freeing pages
Date: Tue, 10 Sep 2013 14:20:32 +0100 [thread overview]
Message-ID: <20130910132032.GO22421@suse.de> (raw)
In-Reply-To: <alpine.DEB.2.02.1309041625060.29607@chino.kir.corp.google.com>
On Wed, Sep 04, 2013 at 04:25:59PM -0700, David Rientjes wrote:
> We've been getting warnings about an excessive amount of time spent
> allocating pages for migration during memory compaction without
> scheduling. isolate_freepages_block() already periodically checks for
> contended locks or the need to schedule, but isolate_freepages() never
> does.
>
> When a zone is massively long and no suitable targets can be found, this
> iteration can be quite expensive without ever doing cond_resched().
>
> Check periodically for the need to reschedule while the compaction free
> scanner iterates.
>
> Signed-off-by: David Rientjes <rientjes@google.com>
Ok, fair enough.
Acked-by: Mel Gorman <mgorman@suse.de>
However I'm curious. Do you know why the combined use of
compact_cached_free_pfn and pageblock skip bits is not enough for the scanner
to quickly find a pageblock that is suitable for isolate_freepages_block()?
Is the pageblock skip information getting cleared frequently by kswapd
or something?
--
Mel Gorman
SUSE Labs
next prev parent reply other threads:[~2013-09-10 13:20 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-04 23:25 [patch] mm, compaction: periodically schedule when freeing pages David Rientjes
2013-09-04 23:25 ` David Rientjes
2013-09-04 23:58 ` Rik van Riel
2013-09-04 23:58 ` Rik van Riel
2013-09-05 0:50 ` Wanpeng Li
2013-09-05 0:50 ` Wanpeng Li
2013-09-10 13:20 ` Mel Gorman [this message]
2013-09-10 13:20 ` Mel Gorman
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