Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]
Groups > linux.kernel > #1379570
| From | Mel Gorman <mgorman@techsingularity.net> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [PATCH 13/28] mm, page_alloc: Remove redundant check for empty zonelist |
| Date | 2016-04-15 11:10 +0200 |
| Message-ID | <ro7Vg-Er-9@gated-at.bofh.it> (permalink) |
| References | <ro7LB-hc-17@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
A check is made for an empty zonelist early in the page allocator fast path but it's unnecessary. When get_page_from_freelist() is called, it'll return NULL immediately. Removing the first check is slower for machines with memoryless nodes but that is a corner case that can live with the overhead. Signed-off-by: Mel Gorman <mgorman@techsingularity.net> --- mm/page_alloc.c | 11 ----------- 1 file changed, 11 deletions(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index df03ccc7f07c..21aaef6ddd7a 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -3374,14 +3374,6 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order, if (should_fail_alloc_page(gfp_mask, order)) return NULL; - /* - * Check the zones suitable for the gfp_mask contain at least one - * valid zone. It's possible to have an empty zonelist as a result - * of __GFP_THISNODE and a memoryless node - */ - if (unlikely(!zonelist->_zonerefs->zone)) - return NULL; - if (IS_ENABLED(CONFIG_CMA) && ac.migratetype == MIGRATE_MOVABLE) alloc_flags |= ALLOC_CMA; @@ -3394,8 +3386,6 @@ __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, &ac.preferred_zone); - if (!ac.preferred_zone) - goto out; ac.classzone_idx = zonelist_zone_idx(preferred_zoneref); /* First allocation attempt */ @@ -3418,7 +3408,6 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order, trace_mm_page_alloc(page, order, alloc_mask, ac.migratetype); -out: /* * When updating a task's mems_allowed, it is possible to race with * parallel threads in such a way that an allocation can fail while -- 2.6.4
Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
[PATCH 00/28] Optimise page alloc/free fast paths v3 Mel Gorman <mgorman@techsingularity.net> - 2016-04-15 11:00 +0200
[PATCH 01/28] mm, page_alloc: Only check PageCompound for high-order pages Mel Gorman <mgorman@techsingularity.net> - 2016-04-15 11:00 +0200
Re: [PATCH 01/28] mm, page_alloc: Only check PageCompound for high-order pages Vlastimil Babka <vbabka@suse.cz> - 2016-04-25 11:40 +0200
Re: [PATCH 01/28] mm, page_alloc: Only check PageCompound for high-order pages Mel Gorman <mgorman@techsingularity.net> - 2016-04-26 12:40 +0200
Re: [PATCH 01/28] mm, page_alloc: Only check PageCompound for high-order pages Vlastimil Babka <vbabka@suse.cz> - 2016-04-26 13:30 +0200
[PATCH 21/28] mm, page_alloc: Avoid looking up the first zone in a zonelist twice Mel Gorman <mgorman@techsingularity.net> - 2016-04-15 11:10 +0200
Re: [PATCH 21/28] mm, page_alloc: Avoid looking up the first zone in a zonelist twice Vlastimil Babka <vbabka@suse.cz> - 2016-04-26 19:50 +0200
[PATCH 04/28] mm, page_alloc: Inline zone_statistics Mel Gorman <mgorman@techsingularity.net> - 2016-04-15 11:10 +0200
Re: [PATCH 04/28] mm, page_alloc: Inline zone_statistics Vlastimil Babka <vbabka@suse.cz> - 2016-04-25 13:20 +0200
[PATCH 15/28] mm, page_alloc: Move might_sleep_if check to the allocator slowpath Mel Gorman <mgorman@techsingularity.net> - 2016-04-15 11:10 +0200
Re: [PATCH 15/28] mm, page_alloc: Move might_sleep_if check to the allocator slowpath Vlastimil Babka <vbabka@suse.cz> - 2016-04-26 15:50 +0200
Re: [PATCH 15/28] mm, page_alloc: Move might_sleep_if check to the allocator slowpath Mel Gorman <mgorman@techsingularity.net> - 2016-04-26 17:00 +0200
Re: [PATCH 15/28] mm, page_alloc: Move might_sleep_if check to the allocator slowpath Vlastimil Babka <vbabka@suse.cz> - 2016-04-26 17:20 +0200
Re: [PATCH 15/28] mm, page_alloc: Move might_sleep_if check to the allocator slowpath Mel Gorman <mgorman@techsingularity.net> - 2016-04-26 18:30 +0200
[PATCH 19/28] mm, page_alloc: Reduce cost of fair zone allocation policy retry Mel Gorman <mgorman@techsingularity.net> - 2016-04-15 11:10 +0200
[PATCH 13/28] mm, page_alloc: Remove redundant check for empty zonelist Mel Gorman <mgorman@techsingularity.net> - 2016-04-15 11:10 +0200
[PATCH 22/28] mm, page_alloc: Remove field from alloc_context Mel Gorman <mgorman@techsingularity.net> - 2016-04-15 11:10 +0200
[PATCH 14/28] mm, page_alloc: Simplify last cpupid reset Mel Gorman <mgorman@techsingularity.net> - 2016-04-15 11:10 +0200
Re: [PATCH 14/28] mm, page_alloc: Simplify last cpupid reset Vlastimil Babka <vbabka@suse.cz> - 2016-04-26 15:40 +0200
[PATCH 20/28] mm, page_alloc: Shortcut watermark checks for order-0 pages Mel Gorman <mgorman@techsingularity.net> - 2016-04-15 11:10 +0200
[PATCH 16/28] mm, page_alloc: Move __GFP_HARDWALL modifications out of the fastpath Mel Gorman <mgorman@techsingularity.net> - 2016-04-15 11:10 +0200
Re: [PATCH 16/28] mm, page_alloc: Move __GFP_HARDWALL modifications out of the fastpath Vlastimil Babka <vbabka@suse.cz> - 2016-04-26 16:20 +0200
[PATCH 17/28] mm, page_alloc: Check once if a zone has isolated pageblocks Mel Gorman <mgorman@techsingularity.net> - 2016-04-15 11:10 +0200
Re: [PATCH 17/28] mm, page_alloc: Check once if a zone has isolated pageblocks Vlastimil Babka <vbabka@suse.cz> - 2016-04-26 16:30 +0200
[PATCH 18/28] mm, page_alloc: Shorten the page allocator fast path Mel Gorman <mgorman@techsingularity.net> - 2016-04-15 11:10 +0200
Re: [PATCH 18/28] mm, page_alloc: Shorten the page allocator fast path Vlastimil Babka <vbabka@suse.cz> - 2016-04-26 17:30 +0200
[PATCH 26/28] cpuset: use static key better and convert to new API Mel Gorman <mgorman@techsingularity.net> - 2016-04-15 11:20 +0200
Re: [PATCH 26/28] cpuset: use static key better and convert to new API Vlastimil Babka <vbabka@suse.cz> - 2016-04-26 22:00 +0200
[PATCH 27/28] mm, page_alloc: Defer debugging checks of freed pages until a PCP drain Mel Gorman <mgorman@techsingularity.net> - 2016-04-15 11:20 +0200
Re: [PATCH 27/28] mm, page_alloc: Defer debugging checks of freed pages until a PCP drain Vlastimil Babka <vbabka@suse.cz> - 2016-04-27 14:00 +0200
[PATCH 2/3] mm, page_alloc: pull out side effects from free_pages_check Vlastimil Babka <vbabka@suse.cz> - 2016-04-27 14:10 +0200
Re: [PATCH 2/3] mm, page_alloc: pull out side effects from free_pages_check Mel Gorman <mgorman@techsingularity.net> - 2016-04-27 14:50 +0200
Re: [PATCH 2/3] mm, page_alloc: pull out side effects from free_pages_check Vlastimil Babka <vbabka@suse.cz> - 2016-04-27 15:10 +0200
[PATCH 3/3] mm, page_alloc: don't duplicate code in free_pcp_prepare Vlastimil Babka <vbabka@suse.cz> - 2016-04-27 14:10 +0200
[PATCH 1/3] mm, page_alloc: un-inline the bad part of free_pages_check Vlastimil Babka <vbabka@suse.cz> - 2016-04-27 14:10 +0200
Re: [PATCH 1/3] mm, page_alloc: un-inline the bad part of free_pages_check Mel Gorman <mgorman@techsingularity.net> - 2016-04-27 14:40 +0200
Re: [PATCH 1/3] mm, page_alloc: un-inline the bad part of free_pages_check Vlastimil Babka <vbabka@suse.cz> - 2016-04-27 15:00 +0200
[PATCH 25/28] mm, page_alloc: Inline pageblock lookup in page free fast paths Mel Gorman <mgorman@techsingularity.net> - 2016-04-15 11:20 +0200
[PATCH 24/28] mm, page_alloc: Remove unnecessary variable from free_pcppages_bulk Mel Gorman <mgorman@techsingularity.net> - 2016-04-15 11:20 +0200
[PATCH 23/28] mm, page_alloc: Check multiple page fields with a single branch Mel Gorman <mgorman@techsingularity.net> - 2016-04-15 11:20 +0200
Re: [PATCH 23/28] mm, page_alloc: Check multiple page fields with a single branch Vlastimil Babka <vbabka@suse.cz> - 2016-04-26 20:50 +0200
Re: [PATCH 23/28] mm, page_alloc: Check multiple page fields with a single branch Mel Gorman <mgorman@techsingularity.net> - 2016-04-27 12:10 +0200
[PATCH 28/28] mm, page_alloc: Defer debugging checks of pages allocated from the PCP Mel Gorman <mgorman@techsingularity.net> - 2016-04-15 11:20 +0200
Re: [PATCH 28/28] mm, page_alloc: Defer debugging checks of pages allocated from the PCP Vlastimil Babka <vbabka@suse.cz> - 2016-04-27 16:10 +0200
Re: [PATCH 28/28] mm, page_alloc: Defer debugging checks of pages allocated from the PCP Mel Gorman <mgorman@techsingularity.net> - 2016-04-27 17:40 +0200
Re: [PATCH 13/28] mm, page_alloc: Remove redundant check for empty zonelist Vlastimil Babka <vbabka@suse.cz> - 2016-04-26 14:10 +0200
Re: [PATCH 13/28] mm, page_alloc: Remove redundant check for empty zonelist Mel Gorman <mgorman@techsingularity.net> - 2016-04-26 15:10 +0200
Re: [PATCH 13/28] mm, page_alloc: Remove redundant check for empty zonelist Andrew Morton <akpm@linux-foundation.org> - 2016-04-26 21:20 +0200
[PATCH 07/28] mm, page_alloc: Avoid unnecessary zone lookups during pageblock operations Mel Gorman <mgorman@techsingularity.net> - 2016-04-15 11:10 +0200
Re: [PATCH 07/28] mm, page_alloc: Avoid unnecessary zone lookups during pageblock operations Vlastimil Babka <vbabka@suse.cz> - 2016-04-26 13:30 +0200
[PATCH 02/28] mm, page_alloc: Use new PageAnonHead helper in the free page fast path Mel Gorman <mgorman@techsingularity.net> - 2016-04-15 11:10 +0200
Re: [PATCH 02/28] mm, page_alloc: Use new PageAnonHead helper in the free page fast path Vlastimil Babka <vbabka@suse.cz> - 2016-04-25 12:00 +0200
[PATCH 11/28] mm, page_alloc: Remove unnecessary initialisation in get_page_from_freelist Mel Gorman <mgorman@techsingularity.net> - 2016-04-15 11:10 +0200
[PATCH 06/28] mm, page_alloc: Use __dec_zone_state for order-0 page allocation Mel Gorman <mgorman@techsingularity.net> - 2016-04-15 11:10 +0200
Re: [PATCH 06/28] mm, page_alloc: Use __dec_zone_state for order-0 page allocation Vlastimil Babka <vbabka@suse.cz> - 2016-04-26 13:30 +0200
[PATCH 09/28] mm, page_alloc: Convert nr_fair_skipped to bool Mel Gorman <mgorman@techsingularity.net> - 2016-04-15 11:10 +0200
Re: [PATCH 09/28] mm, page_alloc: Convert nr_fair_skipped to bool Vlastimil Babka <vbabka@suse.cz> - 2016-04-26 13:40 +0200
[PATCH 08/28] mm, page_alloc: Convert alloc_flags to unsigned Mel Gorman <mgorman@techsingularity.net> - 2016-04-15 11:10 +0200
[PATCH 03/28] mm, page_alloc: Reduce branches in zone_statistics Mel Gorman <mgorman@techsingularity.net> - 2016-04-15 11:10 +0200
Re: [PATCH 03/28] mm, page_alloc: Reduce branches in zone_statistics Vlastimil Babka <vbabka@suse.cz> - 2016-04-25 13:20 +0200
[PATCH 05/28] mm, page_alloc: Inline the fast path of the zonelist iterator Mel Gorman <mgorman@techsingularity.net> - 2016-04-15 11:10 +0200
Re: [PATCH 05/28] mm, page_alloc: Inline the fast path of the zonelist iterator Vlastimil Babka <vbabka@suse.cz> - 2016-04-25 17:00 +0200
Re: [PATCH 05/28] mm, page_alloc: Inline the fast path of the zonelist iterator Mel Gorman <mgorman@techsingularity.net> - 2016-04-26 12:40 +0200
Re: [PATCH 05/28] mm, page_alloc: Inline the fast path of the zonelist iterator Vlastimil Babka <vbabka@suse.cz> - 2016-04-26 13:10 +0200
[PATCH 10/28] mm, page_alloc: Remove unnecessary local variable in get_page_from_freelist Mel Gorman <mgorman@techsingularity.net> - 2016-04-15 11:10 +0200
Re: [PATCH 10/28] mm, page_alloc: Remove unnecessary local variable in get_page_from_freelist Vlastimil Babka <vbabka@suse.cz> - 2016-04-26 13:40 +0200
Re: [PATCH 00/28] Optimise page alloc/free fast paths v3 Jesper Dangaard Brouer <brouer@redhat.com> - 2016-04-15 14:50 +0200
Re: [PATCH 00/28] Optimise page alloc/free fast paths v3 Mel Gorman <mgorman@techsingularity.net> - 2016-04-15 15:10 +0200
[PATCH 12/28] mm, page_alloc: Remove unnecessary initialisation from __alloc_pages_nodemask() Mel Gorman <mgorman@techsingularity.net> - 2016-04-16 09:30 +0200
Re: [PATCH 12/28] mm, page_alloc: Remove unnecessary initialisation from __alloc_pages_nodemask() Vlastimil Babka <vbabka@suse.cz> - 2016-04-26 13:50 +0200
csiph-web