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Message-ID: <1324954208.4634.2.camel@hakkenden.homenet>
Date: Tue, 27 Dec 2011 06:50:08 +0400
From: "Nikolay S." <nowhere@...kenden.ath.cx>
To: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Cc: Dave Chinner <david@...morbit.com>, Michal Hocko <mhocko@...e.cz>,
linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: Kswapd in 3.2.0-rc5 is a CPU hog
В Вт., 27/12/2011 в 11:15 +0900, KAMEZAWA Hiroyuki пишет:
> On Sat, 24 Dec 2011 07:45:03 +1100
> Dave Chinner <david@...morbit.com> wrote:
>
> > On Fri, Dec 23, 2011 at 03:04:02PM +0400, nowhere wrote:
> > > В Пт., 23/12/2011 в 21:20 +1100, Dave Chinner пишет:
> > > > On Fri, Dec 23, 2011 at 01:01:20PM +0400, nowhere wrote:
> > > > > В Чт., 22/12/2011 в 09:55 +1100, Dave Chinner пишет:
> > > > > > On Wed, Dec 21, 2011 at 10:52:49AM +0100, Michal Hocko wrote:
>
> > > Here is the report of trace-cmd while dd'ing
> > > https://80.237.6.56/report-dd.xz
> >
> > Ok, it's not a shrink_slab() problem - it's just being called ~100uS
> > by kswapd. The pattern is:
> >
> > - reclaim 94 (batches of 32,32,30) pages from iinactive list
> > of zone 1, node 0, prio 12
> > - call shrink_slab
> > - scan all caches
> > - all shrinkers return 0 saying nothing to shrink
> > - 40us gap
> > - reclaim 10-30 pages from inactive list of zone 2, node 0, prio 12
> > - call shrink_slab
> > - scan all caches
> > - all shrinkers return 0 saying nothing to shrink
> > - 40us gap
> > - isolate 9 pages from LRU zone ?, node ?, none isolated, none freed
> > - isolate 22 pages from LRU zone ?, node ?, none isolated, none freed
> > - call shrink_slab
> > - scan all caches
> > - all shrinkers return 0 saying nothing to shrink
> > 40us gap
> >
> > And it just repeats over and over again. After a while, nid=0,zone=1
> > drops out of the traces, so reclaim only comes in batches of 10-30
> > pages from zone 2 between each shrink_slab() call.
> >
> > The trace starts at 111209.881s, with 944776 pages on the LRUs. It
> > finishes at 111216.1 with kswapd going to sleep on node 0 with
> > 930067 pages on the LRU. So 7 seconds to free 15,000 pages (call it
> > 2,000 pages/s) which is awfully slow....
> >
> > vmscan gurus - time for you to step in now...
> >
>
> Can you show /proc/zoneinfo ? I want to know each zone's size.
$ cat /proc/zoneinfo
Node 0, zone DMA
pages free 3980
min 64
low 80
high 96
scanned 0
spanned 4080
present 3916
nr_free_pages 3980
nr_inactive_anon 0
nr_active_anon 0
nr_inactive_file 0
nr_active_file 0
nr_unevictable 0
nr_mlock 0
nr_anon_pages 0
nr_mapped 0
nr_file_pages 0
nr_dirty 0
nr_writeback 0
nr_slab_reclaimable 0
nr_slab_unreclaimable 0
nr_page_table_pages 0
nr_kernel_stack 0
nr_unstable 0
nr_bounce 0
nr_vmscan_write 0
nr_vmscan_immediate_reclaim 0
nr_writeback_temp 0
nr_isolated_anon 0
nr_isolated_file 0
nr_shmem 0
nr_dirtied 0
nr_written 0
nr_anon_transparent_hugepages 0
protection: (0, 3503, 4007, 4007)
pagesets
cpu: 0
count: 0
high: 0
batch: 1
vm stats threshold: 4
cpu: 1
count: 0
high: 0
batch: 1
vm stats threshold: 4
all_unreclaimable: 1
start_pfn: 16
inactive_ratio: 1
Node 0, zone DMA32
pages free 19620
min 14715
low 18393
high 22072
scanned 0
spanned 1044480
present 896960
nr_free_pages 19620
nr_inactive_anon 43203
nr_active_anon 206577
nr_inactive_file 412249
nr_active_file 126151
nr_unevictable 7
nr_mlock 7
nr_anon_pages 108557
nr_mapped 6683
nr_file_pages 540415
nr_dirty 5
nr_writeback 0
nr_slab_reclaimable 58887
nr_slab_unreclaimable 12145
nr_page_table_pages 1389
nr_kernel_stack 100
nr_unstable 0
nr_bounce 0
nr_vmscan_write 1021
nr_vmscan_immediate_reclaim 69337
nr_writeback_temp 0
nr_isolated_anon 0
nr_isolated_file 0
nr_shmem 1861
nr_dirtied 1586363
nr_written 1245872
nr_anon_transparent_hugepages 272
protection: (0, 0, 504, 504)
pagesets
cpu: 0
count: 4
high: 186
batch: 31
vm stats threshold: 24
cpu: 1
count: 0
high: 186
batch: 31
vm stats threshold: 24
all_unreclaimable: 0
start_pfn: 4096
inactive_ratio: 5
Node 0, zone Normal
pages free 2854
min 2116
low 2645
high 3174
scanned 0
spanned 131072
present 129024
nr_free_pages 2854
nr_inactive_anon 20682
nr_active_anon 10262
nr_inactive_file 47083
nr_active_file 11292
nr_unevictable 518
nr_mlock 518
nr_anon_pages 22801
nr_mapped 1798
nr_file_pages 58853
nr_dirty 0
nr_writeback 0
nr_slab_reclaimable 4347
nr_slab_unreclaimable 5955
nr_page_table_pages 769
nr_kernel_stack 128
nr_unstable 0
nr_bounce 0
nr_vmscan_write 5285
nr_vmscan_immediate_reclaim 51475
nr_writeback_temp 0
nr_isolated_anon 0
nr_isolated_file 0
nr_shmem 28
nr_dirtied 251597
nr_written 191561
nr_anon_transparent_hugepages 16
protection: (0, 0, 0, 0)
pagesets
cpu: 0
count: 30
high: 186
batch: 31
vm stats threshold: 12
cpu: 1
count: 0
high: 186
batch: 31
vm stats threshold: 12
all_unreclaimable: 0
start_pfn: 1048576
inactive_ratio:
>
> Below is my memo.
>
> In trace log, priority = 11 or 12. Then, I think kswapd can reclaim memory
> to satisfy "sc.nr_reclaimed >= SWAP_CLUSTER_MAX" condition and loops again.
>
> Seeing balance_pgdat() and trace log, I guess it does
>
> wake up
>
> shrink_zone(zone=0(DMA?)) => nothing to reclaim.
> shrink_slab()
> shrink_zone(zone=1(DMA32?)) => reclaim 32,32,31 pages
> shrink_slab()
> shrink_zone(zone=2(NORMAL?)) => reclaim 13 pages.
> srhink_slab()
>
> sleep or retry.
>
> Why shrink_slab() need to be called frequently like this ?
>
> BTW. I'm sorry if I miss something ...Why only kswapd reclaims memory
> while 'dd' operation ? (no direct relcaim by dd.)
> Is this log record cpu hog after 'dd' ?
report-dd.xz is while_ dd.
report-normal.xz - some time after
> Thanks,
> -Kame
>
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