From: Vlastimil Babka <vbabka@suse.cz>
To: Mel Gorman <mgorman@techsingularity.net>,
Andrew Morton <akpm@linux-foundation.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>,
Rik van Riel <riel@redhat.com>,
David Rientjes <rientjes@google.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Michal Hocko <mhocko@kernel.org>, Linux-MM <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 05/12] mm, page_alloc: Remove unecessary recheck of nodemask
Date: Tue, 25 Aug 2015 16:32:05 +0200 [thread overview]
Message-ID: <55DC7C65.8030006@suse.cz> (raw)
In-Reply-To: <1440418191-10894-6-git-send-email-mgorman@techsingularity.net>
On 08/24/2015 02:09 PM, Mel Gorman wrote:
> An allocation request will either use the given nodemask or the cpuset
> current tasks mems_allowed. A cpuset retry will recheck the callers nodemask
> and while it's trivial overhead during an extremely rare operation, also
> unnecessary. This patch fixes it.
>
> Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
> ---
> mm/page_alloc.c | 5 ++---
> 1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 2c1c3bf54d15..32d1cec124bc 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -3171,7 +3171,7 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order,
> gfp_t alloc_mask; /* The gfp_t that was actually used for allocation */
> struct alloc_context ac = {
> .high_zoneidx = gfp_zone(gfp_mask),
> - .nodemask = nodemask,
> + .nodemask = nodemask ? : &cpuset_current_mems_allowed,
Hm this is a functional change for atomic allocations with NULL
nodemask. ac.nodemask is passed down to __alloc_pages_slowpath() which
might determine that ALLOC_CPUSET is not to be used (because it's
atomic). Yet it would use the restricted ac.nodemask in
get_page_from_freelist() and elsewhere.
> .migratetype = gfpflags_to_migratetype(gfp_mask),
> };
>
> @@ -3206,8 +3206,7 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order,
>
> /* The preferred zone is used for statistics later */
> preferred_zoneref = first_zones_zonelist(ac.zonelist, ac.high_zoneidx,
> - ac.nodemask ? : &cpuset_current_mems_allowed,
> - &ac.preferred_zone);
> + ac.nodemask, &ac.preferred_zone);
> if (!ac.preferred_zone)
> goto out;
> ac.classzone_idx = zonelist_zone_idx(preferred_zoneref);
>
next prev parent reply other threads:[~2015-08-25 14:32 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-24 12:09 [PATCH 00/12] Remove zonelist cache and high-order watermark checking v3 Mel Gorman
2015-08-24 12:09 ` [PATCH 01/12] mm, page_alloc: Remove unnecessary parameter from zone_watermark_ok_safe Mel Gorman
2015-08-24 12:09 ` [PATCH 02/12] mm, page_alloc: Remove unnecessary recalculations for dirty zone balancing Mel Gorman
2015-08-24 12:09 ` [PATCH 03/12] mm, page_alloc: Remove unnecessary taking of a seqlock when cpusets are disabled Mel Gorman
2015-08-26 10:25 ` Michal Hocko
2015-08-24 12:09 ` [PATCH 04/12] mm, page_alloc: Only check cpusets when one exists that can be mem-controlled Mel Gorman
2015-08-24 12:37 ` Vlastimil Babka
2015-08-24 13:16 ` Mel Gorman
2015-08-24 20:53 ` Vlastimil Babka
2015-08-25 10:33 ` Mel Gorman
2015-08-25 11:09 ` Vlastimil Babka
2015-08-26 13:41 ` Mel Gorman
2015-08-26 10:46 ` Michal Hocko
2015-08-24 12:09 ` [PATCH 05/12] mm, page_alloc: Remove unecessary recheck of nodemask Mel Gorman
2015-08-25 14:32 ` Vlastimil Babka [this message]
2015-08-24 12:09 ` [PATCH 06/12] mm, page_alloc: Use masks and shifts when converting GFP flags to migrate types Mel Gorman
2015-08-25 14:36 ` Vlastimil Babka
2015-08-24 12:09 ` [PATCH 07/12] mm, page_alloc: Distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd Mel Gorman
2015-08-24 18:29 ` Mel Gorman
2015-08-25 15:37 ` Vlastimil Babka
2015-08-26 14:45 ` Mel Gorman
2015-08-26 16:24 ` Vlastimil Babka
2015-08-26 18:10 ` Mel Gorman
2015-08-27 9:18 ` Vlastimil Babka
2015-08-25 15:48 ` Vlastimil Babka
2015-08-26 13:05 ` Michal Hocko
2015-09-08 6:49 ` Joonsoo Kim
2015-09-09 12:22 ` Mel Gorman
2015-09-18 6:25 ` Joonsoo Kim
2015-08-24 12:09 ` [PATCH 08/12] mm, page_alloc: Rename __GFP_WAIT to __GFP_RECLAIM Mel Gorman
2015-08-26 12:19 ` Vlastimil Babka
2015-08-24 12:09 ` [PATCH 09/12] mm, page_alloc: Delete the zonelist_cache Mel Gorman
2015-08-24 12:29 ` [PATCH 10/12] mm, page_alloc: Remove MIGRATE_RESERVE Mel Gorman
2015-08-24 12:29 ` [PATCH 11/12] mm, page_alloc: Reserve pageblocks for high-order atomic allocations on demand Mel Gorman
2015-08-26 12:44 ` Vlastimil Babka
2015-08-26 14:53 ` Michal Hocko
2015-08-26 15:38 ` Mel Gorman
2015-09-08 8:01 ` Joonsoo Kim
2015-09-09 12:32 ` Mel Gorman
2015-09-18 6:38 ` Joonsoo Kim
2015-09-21 10:51 ` Mel Gorman
2015-08-24 12:30 ` [PATCH 12/12] mm, page_alloc: Only enforce watermarks for order-0 allocations Mel Gorman
2015-08-26 13:42 ` Vlastimil Babka
2015-08-26 14:53 ` Mel Gorman
2015-08-28 12:10 ` Michal Hocko
2015-08-28 14:12 ` Mel Gorman
2015-09-08 8:26 ` Joonsoo Kim
2015-09-09 12:39 ` Mel Gorman
2015-09-18 6:56 ` Joonsoo Kim
2015-09-21 10:51 ` Mel Gorman
2015-09-30 8:51 ` Vitaly Wool
2015-09-30 13:52 ` Vlastimil Babka
2015-09-30 14:16 ` Vitaly Wool
2015-09-30 14:43 ` Vlastimil Babka
2015-09-30 15:18 ` Mel Gorman
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