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[PATCH 16/28] mm, page_alloc: Move __GFP_HARDWALL modifications out of the fastpath

From Mel Gorman <mgorman@techsingularity.net>
Newsgroups linux.kernel
Subject [PATCH 16/28] mm, page_alloc: Move __GFP_HARDWALL modifications out of the fastpath
Date 2016-04-15 11:10 +0200
Message-ID <ro7Vi-Er-45@gated-at.bofh.it> (permalink)
References <ro7LB-hc-17@gated-at.bofh.it> <ro7Vg-Er-9@gated-at.bofh.it>
Organization linux.* mail to news gateway

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__GFP_HARDWALL only has meaning in the context of cpusets but the fast path
always applies the flag on the first attempt. Move the manipulations into
the cpuset paths where they will be masked by a static branch in the common
case.

With the other micro-optimisations in this series combined, the impact on
a page allocator microbenchmark is

                                           4.6.0-rc2                  4.6.0-rc2
                                       decstat-v1r20                micro-v1r20
Min      alloc-odr0-1               381.00 (  0.00%)           377.00 (  1.05%)
Min      alloc-odr0-2               275.00 (  0.00%)           273.00 (  0.73%)
Min      alloc-odr0-4               229.00 (  0.00%)           226.00 (  1.31%)
Min      alloc-odr0-8               199.00 (  0.00%)           196.00 (  1.51%)
Min      alloc-odr0-16              186.00 (  0.00%)           183.00 (  1.61%)
Min      alloc-odr0-32              179.00 (  0.00%)           175.00 (  2.23%)
Min      alloc-odr0-64              174.00 (  0.00%)           172.00 (  1.15%)
Min      alloc-odr0-128             172.00 (  0.00%)           170.00 (  1.16%)
Min      alloc-odr0-256             181.00 (  0.00%)           183.00 ( -1.10%)
Min      alloc-odr0-512             193.00 (  0.00%)           191.00 (  1.04%)
Min      alloc-odr0-1024            201.00 (  0.00%)           199.00 (  1.00%)
Min      alloc-odr0-2048            206.00 (  0.00%)           204.00 (  0.97%)
Min      alloc-odr0-4096            212.00 (  0.00%)           210.00 (  0.94%)
Min      alloc-odr0-8192            215.00 (  0.00%)           213.00 (  0.93%)
Min      alloc-odr0-16384           216.00 (  0.00%)           214.00 (  0.93%)

Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
---
 mm/page_alloc.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 9ef2f4ab9ca5..4a364e318873 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3353,7 +3353,7 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order,
 	struct page *page;
 	unsigned int cpuset_mems_cookie;
 	unsigned int alloc_flags = ALLOC_WMARK_LOW|ALLOC_FAIR;
-	gfp_t alloc_mask; /* The gfp_t that was actually used for allocation */
+	gfp_t alloc_mask = gfp_mask; /* The gfp_t that was actually used for allocation */
 	struct alloc_context ac = {
 		.high_zoneidx = gfp_zone(gfp_mask),
 		.zonelist = zonelist,
@@ -3362,6 +3362,7 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order,
 	};
 
 	if (cpusets_enabled()) {
+		alloc_mask |= __GFP_HARDWALL;
 		alloc_flags |= ALLOC_CPUSET;
 		if (!ac.nodemask)
 			ac.nodemask = &cpuset_current_mems_allowed;
@@ -3389,7 +3390,6 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order,
 	ac.classzone_idx = zonelist_zone_idx(preferred_zoneref);
 
 	/* First allocation attempt */
-	alloc_mask = gfp_mask|__GFP_HARDWALL;
 	page = get_page_from_freelist(alloc_mask, order, alloc_flags, &ac);
 	if (unlikely(!page)) {
 		/*
@@ -3414,8 +3414,10 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order,
 	 * the mask is being updated. If a page allocation is about to fail,
 	 * check if the cpuset changed during allocation and if so, retry.
 	 */
-	if (unlikely(!page && read_mems_allowed_retry(cpuset_mems_cookie)))
+	if (unlikely(!page && read_mems_allowed_retry(cpuset_mems_cookie))) {
+		alloc_mask = gfp_mask;
 		goto retry_cpuset;
+	}
 
 	return page;
 }
-- 
2.6.4

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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

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