From: Mel Gorman <mgorman@suse.de>
To: Rik van Riel <riel@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Konstantin Khlebnikov <khlebnikov@openvz.org>,
Hugh Dickins <hughd@google.com>, Ying Han <yinghan@google.com>,
Linux-MM <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 0/3] Removal of lumpy reclaim V2
Date: Thu, 12 Apr 2012 10:32:09 +0100 [thread overview]
Message-ID: <20120412093209.GM3789@suse.de> (raw)
In-Reply-To: <4F85C813.2050206@redhat.com>
On Wed, Apr 11, 2012 at 02:06:11PM -0400, Rik van Riel wrote:
> On 04/11/2012 01:52 PM, Mel Gorman wrote:
> >On Wed, Apr 11, 2012 at 01:17:02PM -0400, Rik van Riel wrote:
>
> >>Next step: get rid of __GFP_NO_KSWAPD for THP, first
> >>in the -mm kernel
> >>
> >
> >Initially the flag was introduced because kswapd reclaimed too
> >aggressively. One would like to believe that it would be less of a problem
> >now but we must avoid a situation where the CPU and reclaim cost of kswapd
> >exceeds the benefit of allocating a THP.
>
> Since kswapd and the direct reclaim code now use
> the same conditionals for calling compaction,
> the cost ought to be identical.
>
kswapd has different retry logic for reclaim and can stay awake if there
are continual calls to wakeup_kswapd() setting pgdat->kswapd_max_order
and kswapd makes forward progress. It's not identical enough that I would
express 100% confidence that it will be free of problems.
--
Mel Gorman
SUSE Labs
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WARNING: multiple messages have this Message-ID (diff)
From: Mel Gorman <mgorman@suse.de>
To: Rik van Riel <riel@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Konstantin Khlebnikov <khlebnikov@openvz.org>,
Hugh Dickins <hughd@google.com>, Ying Han <yinghan@google.com>,
Linux-MM <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 0/3] Removal of lumpy reclaim V2
Date: Thu, 12 Apr 2012 10:32:09 +0100 [thread overview]
Message-ID: <20120412093209.GM3789@suse.de> (raw)
In-Reply-To: <4F85C813.2050206@redhat.com>
On Wed, Apr 11, 2012 at 02:06:11PM -0400, Rik van Riel wrote:
> On 04/11/2012 01:52 PM, Mel Gorman wrote:
> >On Wed, Apr 11, 2012 at 01:17:02PM -0400, Rik van Riel wrote:
>
> >>Next step: get rid of __GFP_NO_KSWAPD for THP, first
> >>in the -mm kernel
> >>
> >
> >Initially the flag was introduced because kswapd reclaimed too
> >aggressively. One would like to believe that it would be less of a problem
> >now but we must avoid a situation where the CPU and reclaim cost of kswapd
> >exceeds the benefit of allocating a THP.
>
> Since kswapd and the direct reclaim code now use
> the same conditionals for calling compaction,
> the cost ought to be identical.
>
kswapd has different retry logic for reclaim and can stay awake if there
are continual calls to wakeup_kswapd() setting pgdat->kswapd_max_order
and kswapd makes forward progress. It's not identical enough that I would
express 100% confidence that it will be free of problems.
--
Mel Gorman
SUSE Labs
next prev parent reply other threads:[~2012-04-12 9:32 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-11 16:38 [PATCH 0/3] Removal of lumpy reclaim V2 Mel Gorman
2012-04-11 16:38 ` Mel Gorman
2012-04-11 16:38 ` [PATCH 1/3] mm: vmscan: Remove lumpy reclaim Mel Gorman
2012-04-11 16:38 ` Mel Gorman
2012-04-11 17:25 ` Rik van Riel
2012-04-11 17:25 ` Rik van Riel
2012-04-11 18:54 ` KOSAKI Motohiro
2012-04-11 18:54 ` KOSAKI Motohiro
2012-04-11 16:38 ` [PATCH 2/3] mm: vmscan: Do not stall on writeback during memory compaction Mel Gorman
2012-04-11 16:38 ` Mel Gorman
2012-04-11 17:26 ` Rik van Riel
2012-04-11 17:26 ` Rik van Riel
2012-04-11 18:51 ` KOSAKI Motohiro
2012-04-11 18:51 ` KOSAKI Motohiro
2012-04-11 16:38 ` [PATCH 3/3] mm: vmscan: Remove reclaim_mode_t Mel Gorman
2012-04-11 16:38 ` Mel Gorman
2012-04-11 17:26 ` Rik van Riel
2012-04-11 17:26 ` Rik van Riel
2012-04-11 19:48 ` KOSAKI Motohiro
2012-04-11 19:48 ` KOSAKI Motohiro
2012-04-11 17:17 ` [PATCH 0/3] Removal of lumpy reclaim V2 Rik van Riel
2012-04-11 17:17 ` Rik van Riel
2012-04-11 17:52 ` Mel Gorman
2012-04-11 17:52 ` Mel Gorman
2012-04-11 18:06 ` Rik van Riel
2012-04-11 18:06 ` Rik van Riel
2012-04-12 9:32 ` Mel Gorman [this message]
2012-04-12 9:32 ` Mel Gorman
2012-04-11 23:37 ` Ying Han
2012-04-11 23:37 ` Ying Han
2012-04-12 5:49 ` Mel Gorman
2012-04-12 5:49 ` Mel Gorman
2012-04-11 23:54 ` Hugh Dickins
2012-04-11 23:54 ` Hugh Dickins
2012-04-12 5:44 ` Mel Gorman
2012-04-12 5:44 ` Mel Gorman
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