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From: Jia He <hejianet@gmail.com>
To: linux-mm@kvack.org, linux-kernel@vger.kernel.org
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Vlastimil Babka <vbabka@suse.cz>,
	Mel Gorman <mgorman@techsingularity.net>,
	Michal Hocko <mhocko@suse.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	Taku Izumi <izumi.taku@jp.fujitsu.com>,
	Jia He <hejianet@gmail.com>
Subject: [PATCH RFC 0/1] mm, page_alloc: fix incorrect zone_statistics data
Date: Mon, 12 Dec 2016 13:59:06 +0800	[thread overview]
Message-ID: <1481522347-20393-1-git-send-email-hejianet@gmail.com> (raw)


In commit b9f00e147f27 ("mm, page_alloc: reduce branches in
zone_statistics"), it reconstructed the code to reduce the branch miss rate.
Compared with the original logic, it assumed if !(flag & __GFP_OTHER_NODE)
 z->node would not be equal to preferred_zone->node. That seems to be
incorrect.

Here is what I catch, dumpstack() is triggered when z->node ==
preferred_zone->node and z->node != numa_node_id()

z=5,prefer=5,local=4, flag&OTHER_NODE=0
[c000000cdcaef440] [c0000000002e88cc] cache_grow_begin+0xcc/0x500
[c000000cdcaef6f0] [c0000000002ecb44] do_tune_cpucache+0x64/0x100
[c000000cdcaef750] [c0000000002ecc7c] enable_cpucache+0x9c/0x180
[c000000cdcaef7d0] [c0000000002ed01c] __kmem_cache_create+0x1ec/00x2c0
[c000000cdcaef820] [c000000000291c98] create_cache+0xb8/0x240
[c000000cdcaef890] [c000000000291fa8] kmem_cache_create+0x188/0x2290
[c000000cdcaef950] [d000000011dc5c70] ext4_mb_init+0x3c0/0x5e0 [eext4]
[c000000cdcaef9f0] [d000000011daaedc] ext4_fill_super+0x266c/0x33390 [ext4]
[c000000cdcaefb30] [c000000000328b8c] mount_bdev+0x22c/0x260
[c000000cdcaefbd0] [d000000011da1fa8] ext4_mount+0x48/0x60 [ext4]
[c000000cdcaefc10] [c00000000032a11c] mount_fs+0x8c/0x230
[c000000cdcaefcb0] [c000000000351f98] vfs_kern_mount+0x78/0x180
[c000000cdcaefd00] [c000000000356d68] do_mount+0x258/0xea0
[c000000cdcaefde0] [c000000000357da0] SyS_mount+0xa0/0x110
[c000000cdcaefe30] [c00000000000bd84] system_call+0x38/0xe0

Before this patch, the numa_miss and numa_foreign looked very odd:
linux:~ # numastat
                           node0           node1           node2           node3           node4           node5           node6
numa_hit                   42216               0               0               0           96755               0               0
numa_miss                      1             718             711             726             860             712             719
numa_foreign                   1             718             711             726             860             712             719
interleave_hit               631             638             632             641             621             633             636
local_node                 42216               0               0               0           96755               0               0
other_node                     0               0               0               0               0               0               0

After this patch
linux:~ # numastat  
                           node0           node1           node2           node3           node4           node5           node6
numa_hit                  177891             718             711             726           60302             712             719
numa_miss                      0          196944          237222          253424               0           36265               0
numa_foreign              723855               0               0               0               0               0               0
interleave_hit               631             638             632             641             621             633             636
local_node                177891               0               0               0           59444               0               0
other_node                     0             718             711             726             858             712             719
Jia He (1):
  mm, page_alloc: fix incorrect zone_statistics data

 mm/page_alloc.c | 3 +++
 1 file changed, 3 insertions(+)

-- 
2.5.5

WARNING: multiple messages have this Message-ID (diff)
From: Jia He <hejianet@gmail.com>
To: linux-mm@kvack.org, linux-kernel@vger.kernel.org
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Vlastimil Babka <vbabka@suse.cz>,
	Mel Gorman <mgorman@techsingularity.net>,
	Michal Hocko <mhocko@suse.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	Taku Izumi <izumi.taku@jp.fujitsu.com>,
	Jia He <hejianet@gmail.com>
Subject: [PATCH RFC 0/1] mm, page_alloc: fix incorrect zone_statistics data
Date: Mon, 12 Dec 2016 13:59:06 +0800	[thread overview]
Message-ID: <1481522347-20393-1-git-send-email-hejianet@gmail.com> (raw)


In commit b9f00e147f27 ("mm, page_alloc: reduce branches in
zone_statistics"), it reconstructed the code to reduce the branch miss rate.
Compared with the original logic, it assumed if !(flag & __GFP_OTHER_NODE)
 z->node would not be equal to preferred_zone->node. That seems to be
incorrect.

Here is what I catch, dumpstack() is triggered when z->node ==
preferred_zone->node and z->node != numa_node_id()

z=5,prefer=5,local=4, flag&OTHER_NODE=0
[c000000cdcaef440] [c0000000002e88cc] cache_grow_begin+0xcc/0x500
[c000000cdcaef6f0] [c0000000002ecb44] do_tune_cpucache+0x64/0x100
[c000000cdcaef750] [c0000000002ecc7c] enable_cpucache+0x9c/0x180
[c000000cdcaef7d0] [c0000000002ed01c] __kmem_cache_create+0x1ec/00x2c0
[c000000cdcaef820] [c000000000291c98] create_cache+0xb8/0x240
[c000000cdcaef890] [c000000000291fa8] kmem_cache_create+0x188/0x2290
[c000000cdcaef950] [d000000011dc5c70] ext4_mb_init+0x3c0/0x5e0 [eext4]
[c000000cdcaef9f0] [d000000011daaedc] ext4_fill_super+0x266c/0x33390 [ext4]
[c000000cdcaefb30] [c000000000328b8c] mount_bdev+0x22c/0x260
[c000000cdcaefbd0] [d000000011da1fa8] ext4_mount+0x48/0x60 [ext4]
[c000000cdcaefc10] [c00000000032a11c] mount_fs+0x8c/0x230
[c000000cdcaefcb0] [c000000000351f98] vfs_kern_mount+0x78/0x180
[c000000cdcaefd00] [c000000000356d68] do_mount+0x258/0xea0
[c000000cdcaefde0] [c000000000357da0] SyS_mount+0xa0/0x110
[c000000cdcaefe30] [c00000000000bd84] system_call+0x38/0xe0

Before this patch, the numa_miss and numa_foreign looked very odd:
linux:~ # numastat
                           node0           node1           node2           node3           node4           node5           node6
numa_hit                   42216               0               0               0           96755               0               0
numa_miss                      1             718             711             726             860             712             719
numa_foreign                   1             718             711             726             860             712             719
interleave_hit               631             638             632             641             621             633             636
local_node                 42216               0               0               0           96755               0               0
other_node                     0               0               0               0               0               0               0

After this patch
linux:~ # numastat  
                           node0           node1           node2           node3           node4           node5           node6
numa_hit                  177891             718             711             726           60302             712             719
numa_miss                      0          196944          237222          253424               0           36265               0
numa_foreign              723855               0               0               0               0               0               0
interleave_hit               631             638             632             641             621             633             636
local_node                177891               0               0               0           59444               0               0
other_node                     0             718             711             726             858             712             719
Jia He (1):
  mm, page_alloc: fix incorrect zone_statistics data

 mm/page_alloc.c | 3 +++
 1 file changed, 3 insertions(+)

-- 
2.5.5

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             reply	other threads:[~2016-12-12  5:59 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-12-12  5:59 Jia He [this message]
2016-12-12  5:59 ` [PATCH RFC 0/1] mm, page_alloc: fix incorrect zone_statistics data Jia He
2016-12-12  5:59 ` [PATCH RFC 1/1] " Jia He
2016-12-12  5:59   ` Jia He
2016-12-20  9:18   ` Michal Hocko
2016-12-20  9:18     ` Michal Hocko
2016-12-20 13:10     ` Mel Gorman
2016-12-20 13:10       ` Mel Gorman
2016-12-20 13:26       ` Michal Hocko
2016-12-20 13:26         ` Michal Hocko
2016-12-20 14:28         ` Mel Gorman
2016-12-20 14:28           ` Mel Gorman
2016-12-20 14:35           ` Michal Hocko
2016-12-20 14:35             ` Michal Hocko
2016-12-20 14:49             ` Vlastimil Babka
2016-12-20 14:49               ` Vlastimil Babka
2016-12-20 14:54             ` Mel Gorman
2016-12-20 14:54               ` Mel Gorman
2016-12-21  7:57               ` Michal Hocko
2016-12-21  7:57                 ` Michal Hocko
2016-12-21  8:06                 ` [PATCH 1/2] mm: fix remote numa hits statistics Michal Hocko
2016-12-21  8:06                   ` [PATCH 2/2] mm: get rid of __GFP_OTHER_NODE Michal Hocko
2017-01-02 14:18                     ` Vlastimil Babka
2016-12-29 11:46                   ` [PATCH 1/2] mm: fix remote numa hits statistics Mel Gorman
2016-12-29 12:28                     ` Michal Hocko
2017-01-02 14:16                   ` Vlastimil Babka
2017-01-02 14:46                     ` Michal Hocko
2017-01-02 15:07                       ` Vlastimil Babka
2016-12-20 14:42           ` [PATCH RFC 1/1] mm, page_alloc: fix incorrect zone_statistics data Mel Gorman
2016-12-20 14:42             ` Mel Gorman
2016-12-20 15:13     ` Vlastimil Babka
2016-12-20 15:13       ` Vlastimil Babka
2016-12-21  3:01     ` hejianet
2016-12-21  3:01       ` hejianet
2016-12-20 12:31   ` Mel Gorman
2016-12-20 12:31     ` Mel Gorman
2016-12-21  3:07     ` hejianet
2016-12-21  3:07       ` hejianet

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