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Date: Thu, 9 Aug 2012 12:16:35 -0600
From: "Jim Schutt" <jaschut@...dia.gov>
To: "Mel Gorman" <mgorman@...e.de>
cc: Linux-MM <linux-mm@...ck.org>, "Rik van Riel" <riel@...hat.com>,
"Minchan Kim" <minchan@...nel.org>,
LKML <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH 0/5] Improve hugepage allocation success rates
under load V3
On 08/09/2012 07:49 AM, Mel Gorman wrote:
> Changelog since V2
> o Capture !MIGRATE_MOVABLE pages where possible
> o Document the treatment of MIGRATE_MOVABLE pages while capturing
> o Expand changelogs
>
> Changelog since V1
> o Dropped kswapd related patch, basically a no-op and regresses if fixed (minchan)
> o Expanded changelogs a little
>
> Allocation success rates have been far lower since 3.4 due to commit
> [fe2c2a10: vmscan: reclaim at order 0 when compaction is enabled]. This
> commit was introduced for good reasons and it was known in advance that
> the success rates would suffer but it was justified on the grounds that
> the high allocation success rates were achieved by aggressive reclaim.
> Success rates are expected to suffer even more in 3.6 due to commit
> [7db8889a: mm: have order> 0 compaction start off where it left] which
> testing has shown to severely reduce allocation success rates under load -
> to 0% in one case. There is a proposed change to that patch in this series
> and it would be ideal if Jim Schutt could retest the workload that led to
> commit [7db8889a: mm: have order> 0 compaction start off where it left].
On my first test of this patch series on top of 3.5, I ran into an
instance of what I think is the sort of thing that patch 4/5 was
fixing. Here's what vmstat had to say during that period:
----------
2012-08-09 11:58:04.107-06:00
vmstat -w 4 16
procs -------------------memory------------------ ---swap-- -----io---- --system-- -----cpu-------
r b swpd free buff cache si so bi bo in cs us sy id wa st
20 14 0 235884 576 38916072 0 0 12 17047 171 133 3 8 85 4 0
18 17 0 220272 576 38955912 0 0 86 2131838 200142 162956 12 38 31 19 0
17 9 0 244284 576 38955328 0 0 19 2179562 213775 167901 13 43 26 18 0
27 15 0 223036 576 38952640 0 0 24 2202816 217996 158390 14 47 25 15 0
17 16 0 233124 576 38959908 0 0 5 2268815 224647 165728 14 50 21 15 0
16 13 0 225840 576 38995740 0 0 52 2253829 216797 160551 14 47 23 16 0
22 13 0 260584 576 38982908 0 0 92 2196737 211694 140924 14 53 19 15 0
16 10 0 235784 576 38917128 0 0 22 2157466 210022 137630 14 54 19 14 0
12 13 0 214300 576 38923848 0 0 31 2187735 213862 142711 14 52 20 14 0
25 12 0 219528 576 38919540 0 0 11 2066523 205256 142080 13 49 23 15 0
26 14 0 229460 576 38913704 0 0 49 2108654 200692 135447 13 51 21 15 0
11 11 0 220376 576 38862456 0 0 45 2136419 207493 146813 13 49 22 16 0
36 12 0 229860 576 38869784 0 0 7 2163463 212223 151812 14 47 25 14 0
16 13 0 238356 576 38891496 0 0 67 2251650 221728 154429 14 52 20 14 0
65 15 0 211536 576 38922108 0 0 59 2237925 224237 156587 14 53 19 14 0
24 13 0 585024 576 38634024 0 0 37 2240929 229040 148192 15 61 14 10 0
2012-08-09 11:59:04.714-06:00
vmstat -w 4 16
procs -------------------memory------------------ ---swap-- -----io---- --system-- -----cpu-------
r b swpd free buff cache si so bi bo in cs us sy id wa st
43 8 0 794392 576 38382316 0 0 11 20491 576 420 3 10 82 4 0
127 6 0 579328 576 38422156 0 0 21 2006775 205582 119660 12 70 11 7 0
44 5 0 492860 576 38512360 0 0 46 1536525 173377 85320 10 78 7 4 0
218 9 0 585668 576 38271320 0 0 39 1257266 152869 64023 8 83 7 3 0
101 6 0 600168 576 38128104 0 0 10 1438705 160769 68374 9 84 5 3 0
62 5 0 597004 576 38098972 0 0 93 1376841 154012 63912 8 82 7 4 0
61 11 0 850396 576 37808772 0 0 46 1186816 145731 70453 7 78 9 6 0
124 7 0 437388 576 38126320 0 0 15 1208434 149736 57142 7 86 4 3 0
204 11 0 1105816 576 37309532 0 0 20 1327833 145979 52718 7 87 4 2 0
29 8 0 751020 576 37360332 0 0 8 1405474 169916 61982 9 85 4 2 0
38 7 0 626448 576 37333244 0 0 14 1328415 174665 74214 8 84 5 3 0
23 5 0 650040 576 37134280 0 0 28 1351209 179220 71631 8 85 5 2 0
40 10 0 610988 576 37054292 0 0 104 1272527 167530 73527 7 85 5 3 0
79 22 0 2076836 576 35487340 0 0 750 1249934 175420 70124 7 88 3 2 0
58 6 0 431068 576 36934140 0 0 1000 1366234 169675 72524 8 84 5 3 0
134 9 0 574692 576 36784980 0 0 1049 1305543 152507 62639 8 84 4 4 0
2012-08-09 12:00:09.137-06:00
vmstat -w 4 16
procs -------------------memory------------------ ---swap-- -----io---- --system-- -----cpu-------
r b swpd free buff cache si so bi bo in cs us sy id wa st
163 8 0 464308 576 36791368 0 0 11 22210 866 536 3 13 79 4 0
207 14 0 917752 576 36181928 0 0 712 1345376 134598 47367 7 90 1 2 0
123 12 0 685516 576 36296148 0 0 429 1386615 158494 60077 8 84 5 3 0
123 12 0 598572 576 36333728 0 0 1107 1233281 147542 62351 7 84 5 4 0
622 7 0 660768 576 36118264 0 0 557 1345548 151394 59353 7 85 4 3 0
223 11 0 283960 576 36463868 0 0 46 1107160 121846 33006 6 93 1 1 0
104 14 0 3140508 576 33522616 0 0 299 1414709 160879 51422 9 89 1 1 0
100 11 0 1323036 576 35337740 0 0 429 1637733 175817 94471 9 73 10 8 0
91 11 0 673320 576 35918084 0 0 562 1477100 157069 67951 8 83 5 4 0
35 15 0 3486592 576 32983244 0 0 384 1574186 189023 82135 9 81 5 5 0
51 16 0 1428108 576 34962112 0 0 394 1573231 160575 76632 9 76 9 7 0
55 6 0 719548 576 35621284 0 0 425 1483962 160335 79991 8 74 10 7 0
96 7 0 1226852 576 35062608 0 0 803 1531041 164923 70820 9 78 7 6 0
97 8 0 862500 576 35332496 0 0 536 1177949 155969 80769 7 74 13 7 0
23 5 0 6096372 576 30115776 0 0 367 919949 124993 81755 6 62 24 8 0
13 5 0 7427860 576 28368292 0 0 399 915331 153895 102186 6 53 32 9 0
----------
And here's a perf report, captured/displayed with
perf record -g -a sleep 10
perf report --sort symbol --call-graph fractal,5
sometime during that period just after 12:00:09, when
the run queueu was > 100.
----------
Processed 0 events and LOST 1175296!
Check IO/CPU overload!
# Events: 208K cycles
#
# Overhead
Symbol
# ........ .....................................................................................................................................................................................
.................................................................................................................................................................................................
............................................................................................................
#
34.63% [k] _raw_spin_lock_irqsave
|
|--97.30%-- isolate_freepages
| compaction_alloc
| unmap_and_move
| migrate_pages
| compact_zone
| compact_zone_order
| try_to_compact_pages
| __alloc_pages_direct_compact
| __alloc_pages_slowpath
| __alloc_pages_nodemask
| alloc_pages_vma
| do_huge_pmd_anonymous_page
| handle_mm_fault
| do_page_fault
| page_fault
| |
| |--87.39%-- skb_copy_datagram_iovec
| | tcp_recvmsg
| | inet_recvmsg
| | sock_recvmsg
| | sys_recvfrom
| | system_call
| | __recv
| | |
| | --100.00%-- (nil)
| |
| --12.61%-- memcpy
--2.70%-- [...]
14.31% [k] _raw_spin_lock_irq
|
|--98.08%-- isolate_migratepages_range
| compact_zone
| compact_zone_order
| try_to_compact_pages
| __alloc_pages_direct_compact
| __alloc_pages_slowpath
| __alloc_pages_nodemask
| alloc_pages_vma
| do_huge_pmd_anonymous_page
| handle_mm_fault
| do_page_fault
| page_fault
| |
| |--83.93%-- skb_copy_datagram_iovec
| | tcp_recvmsg
| | inet_recvmsg
| | sock_recvmsg
| | sys_recvfrom
| | system_call
| | __recv
| | |
| | --100.00%-- (nil)
| |
| --16.07%-- memcpy
--1.92%-- [...]
5.48% [k] isolate_freepages_block
|
|--99.96%-- isolate_freepages
| compaction_alloc
| unmap_and_move
| migrate_pages
| compact_zone
| compact_zone_order
| try_to_compact_pages
| __alloc_pages_direct_compact
| __alloc_pages_slowpath
| __alloc_pages_nodemask
| alloc_pages_vma
| do_huge_pmd_anonymous_page
| handle_mm_fault
| do_page_fault
| page_fault
| |
| |--86.01%-- skb_copy_datagram_iovec
| | tcp_recvmsg
| | inet_recvmsg
| | sock_recvmsg
| | sys_recvfrom
| | system_call
| | __recv
| | |
| | --100.00%-- (nil)
| |
| --13.99%-- memcpy
--0.04%-- [...]
5.34% [.] ceph_crc32c_le
|
|--99.95%-- 0xb8057558d0065990
--0.05%-- [...]
----------
If I understand what this is telling me, skb_copy_datagram_iovec
is responsible for triggering the calls to isolate_freepages_block,
isolate_migratepages_range, and isolate_freepages?
FWIW, I'm using a Chelsio T4 NIC in these hosts, with jumbo frames
and the Linux TCP stack (i.e., no stateful TCP offload).
-- Jim
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