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* [PATCH RFC 0/1] mm, page_alloc: fix incorrect zone_statistics data
@ 2016-12-12  5:59 Jia He
  2016-12-12  5:59 ` [PATCH RFC 1/1] " Jia He
  0 siblings, 1 reply; 24+ messages in thread
From: Jia He @ 2016-12-12  5:59 UTC (permalink / raw)
  To: linux-mm, linux-kernel
  Cc: Andrew Morton, Vlastimil Babka, Mel Gorman, Michal Hocko,
	Johannes Weiner, Joonsoo Kim, Taku Izumi, Jia He


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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^ permalink raw reply	[flat|nested] 24+ messages in thread
* [PATCH 0/2] numa node stats alternative fix
@ 2017-01-02 15:30 Michal Hocko
  2017-01-02 15:30 ` [PATCH 1/2] mm: fix remote numa hits statistics Michal Hocko
  0 siblings, 1 reply; 24+ messages in thread
From: Michal Hocko @ 2017-01-02 15:30 UTC (permalink / raw)
  To: Andrew Morton
  Cc: Mel Gorman, Vlastimil Babka, Jia He, Andi Kleen, linux-mm, LKML

Hi,
this is an alternative fix for [1] which is currently sitting in the mm
tree.  I believe that the patch 1 is better because it allows to get rid
of __GFP_OTHER_NODE (patch 2) and it uses less branches as well. Vlastimil
has also shown [2] that the patch from Jia He is not fully compatible with
the code before the patch it tries to fix. I do not think that the issue
is serious enough to warrant stable tree inclusion.

Can we have these patches merged instead?

[1] http://lkml.kernel.org/r/1481522347-20393-1-git-send-email-hejianet@gmail.com
[2] http://lkml.kernel.org/r/233ed490-afb9-4644-6d84-c9f888882da2@suse.cz

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^ permalink raw reply	[flat|nested] 24+ messages in thread

end of thread, back to index

Thread overview: 24+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
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
2016-12-20  9:18   ` Michal Hocko
2016-12-20 13:10     ` Mel Gorman
2016-12-20 13:26       ` Michal Hocko
2016-12-20 14:28         ` Mel Gorman
2016-12-20 14:35           ` Michal Hocko
2016-12-20 14:49             ` Vlastimil Babka
2016-12-20 14:54             ` Mel Gorman
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 15:13     ` Vlastimil Babka
2016-12-21  3:01     ` hejianet
2016-12-20 12:31   ` Mel Gorman
2016-12-21  3:07     ` hejianet
2017-01-02 15:30 [PATCH 0/2] numa node stats alternative fix Michal Hocko
2017-01-02 15:30 ` [PATCH 1/2] mm: fix remote numa hits statistics Michal Hocko

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