From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
To: Mel Gorman <mgorman@techsingularity.net>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Linux-MM <linux-mm@kvack.org>, Rik van Riel <riel@surriel.com>,
Vlastimil Babka <vbabka@suse.cz>,
Johannes Weiner <hannes@cmpxchg.org>,
Minchan Kim <minchan@kernel.org>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
LKML <linux-kernel@vger.kernel.org>,
Michael Ellerman <mpe@ellerman.id.au>,
linuxppc-dev@lists.ozlabs.org,
Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>,
Hari Bathini <hbathini@linux.vnet.ibm.com>
Subject: Re: [PATCH 07/34] mm, vmscan: make kswapd reclaim in terms of nodes
Date: Mon, 29 Aug 2016 15:08:44 +0530 [thread overview]
Message-ID: <20160829093844.GA2592@linux.vnet.ibm.com> (raw)
In-Reply-To: <1467970510-21195-8-git-send-email-mgorman@techsingularity.net>
> Patch "mm: vmscan: Begin reclaiming pages on a per-node basis" started
> thinking of reclaim in terms of nodes but kswapd is still zone-centric. This
> patch gets rid of many of the node-based versus zone-based decisions.
>
> o A node is considered balanced when any eligible lower zone is balanced.
> This eliminates one class of age-inversion problem because we avoid
> reclaiming a newer page just because it's in the wrong zone
> o pgdat_balanced disappears because we now only care about one zone being
> balanced.
> o Some anomalies related to writeback and congestion tracking being based on
> zones disappear.
> o kswapd no longer has to take care to reclaim zones in the reverse order
> that the page allocator uses.
> o Most importantly of all, reclaim from node 0 with multiple zones will
> have similar aging and reclaiming characteristics as every
> other node.
>
> Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
> Acked-by: Johannes Weiner <hannes@cmpxchg.org>
> Acked-by: Vlastimil Babka <vbabka@suse.cz>
This patch seems to hurt FA_DUMP functionality. This behaviour is not
seen on v4.7 but only after this patch.
So when a kernel on a multinode machine with memblock_reserve() such
that most of the nodes have zero available memory, kswapd seems to be
consuming 100% of the time.
This is independent of CONFIG_DEFERRED_STRUCT_PAGE, i.e this problem is
seen even with parallel page struct initialization disabled.
top - 13:48:52 up 1:07, 3 users, load average: 15.25, 15.32, 21.18
Tasks: 11080 total, 16 running, 11064 sleeping, 0 stopped, 0 zombie
%Cpu(s): 0.0 us, 2.7 sy, 0.0 ni, 97.3 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st
KiB Mem: 15929941+total, 8637824 used, 15843563+free, 2304 buffers
KiB Swap: 91898816 total, 0 used, 91898816 free. 1381312 cached Mem
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
10824 root 20 0 0 0 0 R 100.000 0.000 65:30.76 kswapd2
10837 root 20 0 0 0 0 R 100.000 0.000 65:31.17 kswapd15
10823 root 20 0 0 0 0 R 97.059 0.000 65:30.85 kswapd1
10825 root 20 0 0 0 0 R 97.059 0.000 65:31.10 kswapd3
10826 root 20 0 0 0 0 R 97.059 0.000 65:31.18 kswapd4
10827 root 20 0 0 0 0 R 97.059 0.000 65:31.08 kswapd5
10828 root 20 0 0 0 0 R 97.059 0.000 65:30.91 kswapd6
10829 root 20 0 0 0 0 R 97.059 0.000 65:31.17 kswapd7
10830 root 20 0 0 0 0 R 97.059 0.000 65:31.17 kswapd8
10831 root 20 0 0 0 0 R 97.059 0.000 65:31.18 kswapd9
10832 root 20 0 0 0 0 R 97.059 0.000 65:31.12 kswapd10
10833 root 20 0 0 0 0 R 97.059 0.000 65:31.19 kswapd11
10834 root 20 0 0 0 0 R 97.059 0.000 65:31.13 kswapd12
10835 root 20 0 0 0 0 R 97.059 0.000 65:31.09 kswapd13
10836 root 20 0 0 0 0 R 97.059 0.000 65:31.18 kswapd14
277155 srikar 20 0 16960 13760 3264 R 52.941 0.001 0:00.37 top
top - 13:48:55 up 1:07, 3 users, load average: 15.23, 15.32, 21.15
Tasks: 11080 total, 16 running, 11064 sleeping, 0 stopped, 0 zombie
%Cpu(s): 0.0 us, 1.0 sy, 0.0 ni, 99.0 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st
KiB Mem: 15929941+total, 8637824 used, 15843563+free, 2304 buffers
KiB Swap: 91898816 total, 0 used, 91898816 free. 1381312 cached Mem
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
10836 root 20 0 0 0 0 R 100.000 0.000 65:33.39 kswapd14
10823 root 20 0 0 0 0 R 100.000 0.000 65:33.05 kswapd1
10824 root 20 0 0 0 0 R 100.000 0.000 65:32.96 kswapd2
10825 root 20 0 0 0 0 R 100.000 0.000 65:33.30 kswapd3
10826 root 20 0 0 0 0 R 100.000 0.000 65:33.38 kswapd4
10827 root 20 0 0 0 0 R 100.000 0.000 65:33.28 kswapd5
10828 root 20 0 0 0 0 R 100.000 0.000 65:33.11 kswapd6
10829 root 20 0 0 0 0 R 100.000 0.000 65:33.37 kswapd7
10830 root 20 0 0 0 0 R 100.000 0.000 65:33.37 kswapd8
10831 root 20 0 0 0 0 R 100.000 0.000 65:33.38 kswapd9
10832 root 20 0 0 0 0 R 100.000 0.000 65:33.32 kswapd10
10833 root 20 0 0 0 0 R 100.000 0.000 65:33.39 kswapd11
10834 root 20 0 0 0 0 R 100.000 0.000 65:33.33 kswapd12
10835 root 20 0 0 0 0 R 100.000 0.000 65:33.29 kswapd13
10837 root 20 0 0 0 0 R 100.000 0.000 65:33.37 kswapd15
277155 srikar 20 0 17536 14912 3264 R 9.091 0.001 0:00.57 top
1092 root rt 0 0 0 0 S 0.455 0.000 0:00.08 watchdog/178
Please see that there is no used swap space. However 15 kswapd threads
corresponding to 15 out of the 16 nodes are running full throttle. The
only node 0 has memory, other nodes memory is fully reserved.
git bisect output
I tried git bisect between v4.7 and v4.8-rc3 filtered to mm/vmscan.c
# bad: [d7f05528eedb047efe2288cff777676b028747b6] mm, vmscan: account for skipped pages as a partial scan
# good: [b1123ea6d3b3da25af5c8a9d843bd07ab63213f4] mm: balloon: use general non-lru movable page feature
git bisect start 'HEAD' 'b1123ea6' '--' 'mm/vmscan.c'
# bad: [c4a25635b60d08853a3e4eaae3ab34419a36cfa2] mm: move vmscan writes and file write accounting to the node
git bisect bad c4a25635b60d08853a3e4eaae3ab34419a36cfa2
# bad: [38087d9b0360987a6db46c2c2c4ece37cd048abe] mm, vmscan: simplify the logic deciding whether kswapd sleeps
git bisect bad 38087d9b0360987a6db46c2c2c4ece37cd048abe
# good: [b2e18757f2c9d1cdd746a882e9878852fdec9501] mm, vmscan: begin reclaiming pages on a per-node basis
git bisect good b2e18757f2c9d1cdd746a882e9878852fdec9501
# bad: [1d82de618ddde0f1164e640f79af152f01994c18] mm, vmscan: make kswapd reclaim in terms of nodes
git bisect bad 1d82de618ddde0f1164e640f79af152f01994c18
# good: [f7b60926ebc05944f73d93ffaf6690503b796a88] mm, vmscan: have kswapd only scan based on the highest requested zone
git bisect good f7b60926ebc05944f73d93ffaf6690503b796a88
# first bad commit: [1d82de618ddde0f1164e640f79af152f01994c18] mm, vmscan: make kswapd reclaim in terms of nodes
Here is perf top output on the kernel where kswapd is hogging cpu.
- 93.50% 0.01% [kernel] [k] kswapd
- kswapd
- 114.31% shrink_node
- 111.51% shrink_node_memcg
- pgdat_reclaimable
- 95.51% pgdat_reclaimable_pages
- 86.34% pgdat_reclaimable_pages
- 6.69% _find_next_bit.part.0
- 2.47% find_next_bit
- 14.46% pgdat_reclaimable
1.13% _find_next_bit.part.0
+ 0.30% find_next_bit
- 2.38% shrink_slab
- super_cache_count
- 0
- __list_lru_count_one.isra.1
_raw_spin_lock
- 28.04% pgdat_reclaimable
- 23.97% pgdat_reclaimable_pages
- 21.66% pgdat_reclaimable_pages
- 1.69% _find_next_bit.part.0
0.63% find_next_bit
- 3.70% pgdat_reclaimable
0.29% _find_next_bit.part.0
- 16.33% zone_balanced
- zone_watermark_ok_safe
- 14.86% zone_watermark_ok_safe
1.15% _find_next_bit.part.0
0.31% find_next_bit
- 2.72% prepare_kswapd_sleep
- zone_balanced
- zone_watermark_ok_safe
zone_watermark_ok_safe
- 80.72% 10.51% [kernel] [k] pgdat_reclaimable
- 140.49% pgdat_reclaimable
- 138.40% pgdat_reclaimable_pages
- 125.10% pgdat_reclaimable_pages
- 9.71% _find_next_bit.part.0
- 3.59% find_next_bit
1.64% _find_next_bit.part.0
+ 0.44% find_next_bit
- 21.03% ret_from_kernel_thread
kthread
- kswapd
- 16.75% shrink_node
shrink_node_memcg
- 4.28% pgdat_reclaimable
pgdat_reclaimable
- 69.17% 62.48% [kernel] [k] pgdat_reclaimable_pages
- 145.91% ret_from_kernel_thread
kthread
- 15.61% pgdat_reclaimable_pages
- 11.33% _find_next_bit.part.0
- 4.19% find_next_bit
- 66.18% 0.01% [kernel] [k] shrink_node
- shrink_node
- 157.54% shrink_node_memcg
- pgdat_reclaimable
- 134.94% pgdat_reclaimable_pages
- 121.99% pgdat_reclaimable_pages
- 9.46% _find_next_bit.part.0
- 3.49% find_next_bit
- 20.44% pgdat_reclaimable
1.59% _find_next_bit.part.0
+ 0.42% find_next_bit
- 3.37% shrink_slab
- super_cache_count
- 0
- __list_lru_count_one.isra.1
_raw_spin_lock
- 64.56% 0.03% [kernel] [k] shrink_node_memcg
- shrink_node_memcg
- pgdat_reclaimable
- 138.31% pgdat_reclaimable_pages
- 125.04% pgdat_reclaimable_pages
- 9.69% _find_next_bit.part.0
- 3.58% find_next_bit
- 20.95% pgdat_reclaimable
1.63% _find_next_bit.part.0
+ 0.43% find_next_bit
53.73% 0.00% [kernel] [k] kthread
53.73% 0.00% [kernel] [k] ret_from_kernel_thread
- 11.04% 10.04% [kernel] [k] zone_watermark_ok_safe
- 146.80% ret_from_kernel_thread
kthread
- kswapd
- 125.81% zone_balanced
zone_watermark_ok_safe
- 20.97% prepare_kswapd_sleep
zone_balanced
zone_watermark_ok_safe
- 14.55% zone_watermark_ok_safe
11.38% _find_next_bit.part.0
3.06% find_next_bit
- 11.03% 0.00% [kernel] [k] zone_balanced
- zone_balanced
- zone_watermark_ok_safe
145.84% zone_watermark_ok_safe
11.31% _find_next_bit.part.0
3.04% find_next_bit
--
Thanks and Regards
Srikar Dronamraju
next prev parent reply other threads:[~2016-08-29 9:40 UTC|newest]
Thread overview: 109+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-08 9:34 [PATCH 00/34] Move LRU page reclaim from zones to nodes v9 Mel Gorman
2016-07-08 9:34 ` [PATCH 01/34] mm, vmstat: add infrastructure for per-node vmstats Mel Gorman
2016-08-03 19:13 ` Reza Arbab
2016-07-08 9:34 ` [PATCH 02/34] mm, vmscan: move lru_lock to the node Mel Gorman
2016-07-12 11:06 ` Balbir Singh
2016-07-12 11:18 ` Mel Gorman
2016-07-13 5:50 ` Balbir Singh
2016-07-13 8:39 ` Vlastimil Babka
2016-07-08 9:34 ` [PATCH 03/34] mm, vmscan: move LRU lists to node Mel Gorman
2016-08-04 20:59 ` James Hogan
2016-08-05 8:41 ` Mel Gorman
2016-08-05 10:52 ` James Hogan
2016-08-05 11:55 ` Mel Gorman
2016-08-05 12:02 ` James Hogan
2016-07-08 9:34 ` [PATCH 04/34] mm, mmzone: clarify the usage of zone padding Mel Gorman
2016-07-12 13:49 ` Johannes Weiner
2016-07-08 9:34 ` [PATCH 05/34] mm, vmscan: begin reclaiming pages on a per-node basis Mel Gorman
2016-07-12 13:54 ` Johannes Weiner
2016-07-14 9:19 ` Vlastimil Babka
2016-07-08 9:34 ` [PATCH 06/34] mm, vmscan: have kswapd only scan based on the highest requested zone Mel Gorman
2016-07-12 14:05 ` Johannes Weiner
2016-07-13 8:37 ` Mel Gorman
2016-07-08 9:34 ` [PATCH 07/34] mm, vmscan: make kswapd reclaim in terms of nodes Mel Gorman
2016-08-29 9:38 ` Srikar Dronamraju [this message]
2016-08-30 12:07 ` Mel Gorman
2016-08-30 14:25 ` Srikar Dronamraju
2016-08-30 15:00 ` Mel Gorman
2016-08-31 6:09 ` Srikar Dronamraju
2016-08-31 8:49 ` Mel Gorman
2016-08-31 11:09 ` Michal Hocko
2016-08-31 12:46 ` Mel Gorman
2016-08-31 17:33 ` Srikar Dronamraju
2016-07-08 9:34 ` [PATCH 08/34] mm, vmscan: remove balance gap Mel Gorman
2016-07-12 14:06 ` Johannes Weiner
2016-07-08 9:34 ` [PATCH 09/34] mm, vmscan: simplify the logic deciding whether kswapd sleeps Mel Gorman
2016-07-08 9:34 ` [PATCH 10/34] mm, vmscan: by default have direct reclaim only shrink once per node Mel Gorman
2016-07-08 9:34 ` [PATCH 11/34] mm, vmscan: remove duplicate logic clearing node congestion and dirty state Mel Gorman
2016-07-12 14:22 ` Johannes Weiner
2016-07-13 8:40 ` Mel Gorman
2016-07-14 9:45 ` Vlastimil Babka
2016-07-08 9:34 ` [PATCH 12/34] mm: vmscan: do not reclaim from kswapd if there is any eligible zone Mel Gorman
2016-07-12 14:29 ` Johannes Weiner
2016-07-13 8:47 ` Mel Gorman
2016-07-13 12:28 ` Johannes Weiner
2016-07-08 9:34 ` [PATCH 13/34] mm, vmscan: make shrink_node decisions more node-centric Mel Gorman
2016-07-12 14:32 ` Johannes Weiner
2016-07-13 8:48 ` Mel Gorman
2016-07-08 9:34 ` [PATCH 14/34] mm, memcg: move memcg limit enforcement from zones to nodes Mel Gorman
2016-07-12 14:38 ` Johannes Weiner
2016-07-08 9:34 ` [PATCH 15/34] mm, workingset: make working set detection node-aware Mel Gorman
2016-07-08 9:34 ` [PATCH 16/34] mm, page_alloc: consider dirtyable memory in terms of nodes Mel Gorman
2016-07-08 9:34 ` [PATCH 17/34] mm: move page mapped accounting to the node Mel Gorman
2016-07-12 14:42 ` Johannes Weiner
2016-07-08 9:34 ` [PATCH 18/34] mm: rename NR_ANON_PAGES to NR_ANON_MAPPED Mel Gorman
2016-07-12 14:58 ` Johannes Weiner
2016-07-13 8:55 ` Mel Gorman
2016-07-13 13:04 ` Johannes Weiner
2016-07-13 13:37 ` Mel Gorman
2016-07-13 21:13 ` Andrew Morton
2016-07-15 10:46 ` Mel Gorman
2016-07-15 22:35 ` Andrew Morton
2016-07-18 13:34 ` Johannes Weiner
2016-07-14 1:27 ` Minchan Kim
2016-07-08 9:34 ` [PATCH 19/34] mm: move most file-based accounting to the node Mel Gorman
2016-07-12 15:11 ` Johannes Weiner
2016-07-08 9:34 ` [PATCH 20/34] mm: move vmscan writes and file write " Mel Gorman
2016-07-12 15:15 ` Johannes Weiner
2016-07-08 9:34 ` [PATCH 21/34] mm, vmscan: only wakeup kswapd once per node for the requested classzone Mel Gorman
2016-07-12 17:18 ` Johannes Weiner
2016-07-08 9:34 ` [PATCH 22/34] mm, page_alloc: wake kswapd based on the highest eligible zone Mel Gorman
2016-07-12 17:24 ` Johannes Weiner
2016-07-14 10:05 ` Vlastimil Babka
2016-07-08 9:34 ` [PATCH 23/34] mm: convert zone_reclaim to node_reclaim Mel Gorman
2016-07-12 17:28 ` Johannes Weiner
2016-07-08 9:35 ` [PATCH 24/34] mm, vmscan: avoid passing in classzone_idx unnecessarily to shrink_node Mel Gorman
2016-07-12 17:31 ` Johannes Weiner
2016-07-14 10:09 ` Vlastimil Babka
2016-07-08 9:35 ` [PATCH 25/34] mm, vmscan: avoid passing in classzone_idx unnecessarily to compaction_ready Mel Gorman
2016-07-12 18:01 ` Johannes Weiner
2016-07-14 12:12 ` Vlastimil Babka
2016-07-08 9:35 ` [PATCH 26/34] mm, vmscan: avoid passing in remaining unnecessarily to prepare_kswapd_sleep Mel Gorman
2016-07-12 18:06 ` Johannes Weiner
2016-07-14 12:48 ` Vlastimil Babka
2016-07-08 9:35 ` [PATCH 27/34] mm, vmscan: Have kswapd reclaim from all zones if reclaiming and buffer_heads_over_limit Mel Gorman
2016-07-12 18:10 ` Johannes Weiner
2016-07-14 12:54 ` Vlastimil Babka
2016-07-08 9:35 ` [PATCH 28/34] mm, vmscan: add classzone information to tracepoints Mel Gorman
2016-07-12 18:13 ` Johannes Weiner
2016-07-08 9:35 ` [PATCH 29/34] mm, page_alloc: remove fair zone allocation policy Mel Gorman
2016-07-12 18:18 ` Johannes Weiner
2016-07-08 9:35 ` [PATCH 30/34] mm: page_alloc: cache the last node whose dirty limit is reached Mel Gorman
2016-07-12 18:43 ` Johannes Weiner
2016-07-08 9:35 ` [PATCH 31/34] mm: vmstat: replace __count_zone_vm_events with a zone id equivalent Mel Gorman
2016-07-12 19:10 ` Johannes Weiner
2016-07-08 9:35 ` [PATCH 32/34] mm: vmstat: account per-zone stalls and pages skipped during reclaim Mel Gorman
2016-07-12 19:06 ` Johannes Weiner
2016-07-08 9:35 ` [PATCH 33/34] mm, vmstat: print node-based stats in zoneinfo file Mel Gorman
2016-07-12 19:18 ` Johannes Weiner
2016-07-14 12:56 ` Vlastimil Babka
2016-07-08 9:35 ` [PATCH 34/34] mm, vmstat: remove zone and node double accounting by approximating retries Mel Gorman
2016-07-14 13:40 ` Vlastimil Babka
2016-07-15 7:48 ` Mel Gorman
2016-07-15 12:20 ` Vlastimil Babka
2016-08-19 13:12 ` [PATCH 00/34] Move LRU page reclaim from zones to nodes v9 Andrea Arcangeli
2016-08-19 13:23 ` Vlastimil Babka
2016-08-19 13:55 ` Andrea Arcangeli
2016-08-19 14:53 ` Mel Gorman
2016-08-19 15:32 ` Andrea Arcangeli
2016-08-19 15:55 ` Mel Gorman
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