From: Andrea Arcangeli <aarcange@redhat.com>
To: Mel Gorman <mel@csn.ul.ie>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
Andrew Morton <akpm@linux-foundation.org>,
Rik van Riel <riel@redhat.com>,
Johannes Weiner <hannes@cmpxchg.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 6/8] mm: compaction: Perform a faster scan in try_to_compact_pages()
Date: Thu, 18 Nov 2010 19:34:48 +0100 [thread overview]
Message-ID: <20101118183448.GC30376@random.random> (raw)
In-Reply-To: <1290010969-26721-7-git-send-email-mel@csn.ul.ie>
On Wed, Nov 17, 2010 at 04:22:47PM +0000, Mel Gorman wrote:
> @@ -485,8 +500,8 @@ static unsigned long compact_zone_order(struct zone *zone,
> .nr_migratepages = 0,
> .order = order,
> .migratetype = allocflags_to_migratetype(gfp_mask),
> + .migrate_fast_scan = true,
> .zone = zone,
> - .sync = false,
> };
> INIT_LIST_HEAD(&cc.freepages);
> INIT_LIST_HEAD(&cc.migratepages);
> @@ -502,8 +517,8 @@ unsigned long reclaimcompact_zone_order(struct zone *zone,
> .nr_migratepages = 0,
> .order = order,
> .migratetype = allocflags_to_migratetype(gfp_mask),
> + .migrate_fast_scan = false,
> .zone = zone,
> - .sync = true,
> };
Same as for the previous feature (sync/async migrate) I'd prefer if
this was a __GFP_ flag (khugepaged will do the no-fast-scan version,
page fault will only run compaction in fast scan mode) and if we
removed the reclaimcompact_zone_order and we stick with the
interleaving of shrinker and try_to_compact_pages from the alloc_pages
caller, with no nesting of compaction inside the shrinker.
Another possibility would be to not have those as __GFP flags, and to
always do the first try_to_compact_pages with async+fast_scan, then
call the shrinker and then all next try_to_compact_pages would be
called with sync+no_fast_scan mode.
But I love if we can further decrease the risk of too long page
hugepage page fault before the normal page fallback, and to have a
__GFP_ flag for these two. Even the same __GFP flag could work for
both...
So my preference would be to nuke reclaimcompact_zone_order, only
stick to compact_zone_order and the current interleaving, and add a
__GFP_COMPACT_FAST used by the hugepmd page fault (that will enable
both async migrate and fast-scan). khugepaged and hugetlbfs won't use
__GFP_COMPACT_FAST.
I'm undecided if a __GFP_ flag is needed to differentiate the callers,
or if we should just run the first try_to_compact_pages in
"optimistic" mode by default.
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next prev parent reply other threads:[~2010-11-18 18:35 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-11-17 16:22 [PATCH 0/8] Use memory compaction instead of lumpy reclaim during high-order allocations Mel Gorman
2010-11-17 16:22 ` [PATCH 1/8] mm: compaction: Add trace events for memory compaction activity Mel Gorman
2010-11-17 16:22 ` [PATCH 2/8] mm: vmscan: Convert lumpy_mode into a bitmask Mel Gorman
2010-11-17 16:22 ` [PATCH 3/8] mm: vmscan: Reclaim order-0 and use compaction instead of lumpy reclaim Mel Gorman
2010-11-18 18:09 ` Andrea Arcangeli
2010-11-18 18:30 ` Mel Gorman
2010-11-17 16:22 ` [PATCH 4/8] mm: migration: Allow migration to operate asynchronously and avoid synchronous compaction in the faster path Mel Gorman
2010-11-18 18:21 ` Andrea Arcangeli
2010-11-18 18:34 ` Mel Gorman
2010-11-18 19:00 ` Andrea Arcangeli
2010-11-17 16:22 ` [PATCH 5/8] mm: migration: Cleanup migrate_pages API by matching types for offlining and sync Mel Gorman
2010-11-17 16:22 ` [PATCH 6/8] mm: compaction: Perform a faster scan in try_to_compact_pages() Mel Gorman
2010-11-18 18:34 ` Andrea Arcangeli [this message]
2010-11-18 18:50 ` Mel Gorman
2010-11-18 19:08 ` Andrea Arcangeli
2010-11-19 11:16 ` Mel Gorman
2010-11-17 16:22 ` [PATCH 7/8] mm: compaction: Use the LRU to get a hint on where compaction should start Mel Gorman
2010-11-18 9:10 ` KAMEZAWA Hiroyuki
2010-11-18 9:28 ` Mel Gorman
2010-11-18 18:46 ` Andrea Arcangeli
2010-11-19 11:08 ` Mel Gorman
2010-11-17 16:22 ` [PATCH 8/8] mm: vmscan: Rename lumpy_mode to reclaim_mode Mel Gorman
2010-11-17 23:46 ` [PATCH 0/8] Use memory compaction instead of lumpy reclaim during high-order allocations Andrew Morton
2010-11-18 2:03 ` Rik van Riel
2010-11-18 8:12 ` Mel Gorman
2010-11-18 8:26 ` KAMEZAWA Hiroyuki
2010-11-18 8:38 ` Johannes Weiner
2010-11-18 9:20 ` Mel Gorman
2010-11-18 19:49 ` Andrew Morton
2010-11-19 10:48 ` Mel Gorman
2010-11-19 12:43 ` Theodore Tso
2010-11-19 14:05 ` Mel Gorman
2010-11-19 15:45 ` Ted Ts'o
2010-11-18 8:44 ` Mel Gorman
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