There is little motiviation for reclaim_mode_t once RECLAIM_MODE_[A]SYNC
and lumpy reclaim have been removed. This patch gets rid of
reclaim_mode_t as well and improves the documentation about what
reclaim/compaction is and when it is triggered.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Konstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ying Han <yinghan@google.com>
Cc: Andy Whitcroft <apw@shadowen.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch stops reclaim/compaction entering sync reclaim as this was
only intended for lumpy reclaim and an oversight. Page migration has
its own logic for stalling on writeback pages if necessary and memory
compaction is already using it.
Waiting on page writeback is bad for a number of reasons but the primary
one is that waiting on writeback to a slow device like USB can take a
considerable length of time. Page reclaim instead uses
wait_iff_congested() to throttle if too many dirty pages are being
scanned.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Konstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ying Han <yinghan@google.com>
Cc: Andy Whitcroft <apw@shadowen.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This series removes lumpy reclaim and some stalling logic that was
unintentionally being used by memory compaction. The end result is that
stalling on dirty pages during page reclaim now depends on
wait_iff_congested().
Four kernels were compared
3.3.0 vanilla
3.4.0-rc2 vanilla
3.4.0-rc2 lumpyremove-v2 is patch one from this series
3.4.0-rc2 nosync-v2r3 is the full series
Removing lumpy reclaim saves almost 900 bytes of text whereas the full
series removes 1200 bytes.
text data bss dec hex filename
6740375 1927944 2260992 10929311 a6c49f vmlinux-3.4.0-rc2-vanilla
6739479 1927944 2260992 10928415 a6c11f vmlinux-3.4.0-rc2-lumpyremove-v2
6739159 1927944 2260992 10928095 a6bfdf vmlinux-3.4.0-rc2-nosync-v2
There are behaviour changes in the series and so tests were run with
monitoring of ftrace events. This disrupts results so the performance
results are distorted but the new behaviour should be clearer.
fs-mark running in a threaded configuration showed little of interest as
it did not push reclaim aggressively
FS-Mark Multi Threaded
3.3.0-vanilla rc2-vanilla lumpyremove-v2r3 nosync-v2r3
Files/s min 3.20 ( 0.00%) 3.20 ( 0.00%) 3.20 ( 0.00%) 3.20 ( 0.00%)
Files/s mean 3.20 ( 0.00%) 3.20 ( 0.00%) 3.20 ( 0.00%) 3.20 ( 0.00%)
Files/s stddev 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%)
Files/s max 3.20 ( 0.00%) 3.20 ( 0.00%) 3.20 ( 0.00%) 3.20 ( 0.00%)
Overhead min 508667.00 ( 0.00%) 521350.00 (-2.49%) 544292.00 (-7.00%) 547168.00 (-7.57%)
Overhead mean 551185.00 ( 0.00%) 652690.73 (-18.42%) 991208.40 (-79.83%) 570130.53 (-3.44%)
Overhead stddev 18200.69 ( 0.00%) 331958.29 (-1723.88%) 1579579.43 (-8578.68%) 9576.81 (47.38%)
Overhead max 576775.00 ( 0.00%) 1846634.00 (-220.17%) 6901055.00 (-1096.49%) 585675.00 (-1.54%)
MMTests Statistics: duration
Sys Time Running Test (seconds) 309.90 300.95 307.33 298.95
User+Sys Time Running Test (seconds) 319.32 309.67 315.69 307.51
Total Elapsed Time (seconds) 1187.85 1193.09 1191.98 1193.73
MMTests Statistics: vmstat
Page Ins 80532 82212 81420 79480
Page Outs 111434984 111456240 111437376 111582628
Swap Ins 0 0 0 0
Swap Outs 0 0 0 0
Direct pages scanned 44881 27889 27453 34843
Kswapd pages scanned 25841428 25860774 25861233 25843212
Kswapd pages reclaimed 25841393 25860741 25861199 25843179
Direct pages reclaimed 44881 27889 27453 34843
Kswapd efficiency 99% 99% 99% 99%
Kswapd velocity 21754.791 21675.460 21696.029 21649.127
Direct efficiency 100% 100% 100% 100%
Direct velocity 37.783 23.375 23.031 29.188
Percentage direct scans 0% 0% 0% 0%
ftrace showed that there was no stalling on writeback or pages submitted
for IO from reclaim context.
postmark was similar and while it was more interesting, it also did not
push reclaim heavily.
POSTMARK
3.3.0-vanilla rc2-vanilla lumpyremove-v2r3 nosync-v2r3
Transactions per second: 16.00 ( 0.00%) 20.00 (25.00%) 18.00 (12.50%) 17.00 ( 6.25%)
Data megabytes read per second: 18.80 ( 0.00%) 24.27 (29.10%) 22.26 (18.40%) 20.54 ( 9.26%)
Data megabytes written per second: 35.83 ( 0.00%) 46.25 (29.08%) 42.42 (18.39%) 39.14 ( 9.24%)
Files created alone per second: 28.00 ( 0.00%) 38.00 (35.71%) 34.00 (21.43%) 30.00 ( 7.14%)
Files create/transact per second: 8.00 ( 0.00%) 10.00 (25.00%) 9.00 (12.50%) 8.00 ( 0.00%)
Files deleted alone per second: 556.00 ( 0.00%) 1224.00 (120.14%) 3062.00 (450.72%) 6124.00 (1001.44%)
Files delete/transact per second: 8.00 ( 0.00%) 10.00 (25.00%) 9.00 (12.50%) 8.00 ( 0.00%)
MMTests Statistics: duration
Sys Time Running Test (seconds) 113.34 107.99 109.73 108.72
User+Sys Time Running Test (seconds) 145.51 139.81 143.32 143.55
Total Elapsed Time (seconds) 1159.16 899.23 980.17 1062.27
MMTests Statistics: vmstat
Page Ins 13710192 13729032 13727944 13760136
Page Outs 43071140 42987228 42733684 42931624
Swap Ins 0 0 0 0
Swap Outs 0 0 0 0
Direct pages scanned 0 0 0 0
Kswapd pages scanned 9941613 9937443 9939085 9929154
Kswapd pages reclaimed 9940926 9936751 9938397 9928465
Direct pages reclaimed 0 0 0 0
Kswapd efficiency 99% 99% 99% 99%
Kswapd velocity 8576.567 11051.058 10140.164 9347.109
Direct efficiency 100% 100% 100% 100%
Direct velocity 0.000 0.000 0.000 0.000
It looks like here that the full series regresses performance but as
ftrace showed no usage of wait_iff_congested() or sync reclaim I am
assuming it's a disruption due to monitoring. Other data such as memory
usage, page IO, swap IO all looked similar.
Running a benchmark with a plain DD showed nothing very interesting.
The full series stalled in wait_iff_congested() slightly less but stall
times on vanilla kernels were marginal.
Running a benchmark that hammered on file-backed mappings showed stalls
due to congestion but not in sync writebacks
MICRO
3.3.0-vanilla rc2-vanilla lumpyremove-v2r3 nosync-v2r3
MMTests Statistics: duration
Sys Time Running Test (seconds) 308.13 294.50 298.75 299.53
User+Sys Time Running Test (seconds) 330.45 316.28 318.93 320.79
Total Elapsed Time (seconds) 1814.90 1833.88 1821.14 1832.91
MMTests Statistics: vmstat
Page Ins 108712 120708 97224 110344
Page Outs 155514576 156017404 155813676 156193256
Swap Ins 0 0 0 0
Swap Outs 0 0 0 0
Direct pages scanned 2599253 1550480 2512822 2414760
Kswapd pages scanned 69742364 71150694 68839041 69692533
Kswapd pages reclaimed 34824488 34773341 34796602 34799396
Direct pages reclaimed 53693 94750 61792 75205
Kswapd efficiency 49% 48% 50% 49%
Kswapd velocity 38427.662 38797.901 37799.972 38022.889
Direct efficiency 2% 6% 2% 3%
Direct velocity 1432.174 845.464 1379.807 1317.446
Percentage direct scans 3% 2% 3% 3%
Page writes by reclaim 0 0 0 0
Page writes file 0 0 0 0
Page writes anon 0 0 0 0
Page reclaim immediate 0 0 0 1218
Page rescued immediate 0 0 0 0
Slabs scanned 15360 16384 13312 16384
Direct inode steals 0 0 0 0
Kswapd inode steals 4340 4327 1630 4323
FTrace Reclaim Statistics: congestion_wait
Direct number congest waited 0 0 0 0
Direct time congest waited 0ms 0ms 0ms 0ms
Direct full congest waited 0 0 0 0
Direct number conditional waited 900 870 754 789
Direct time conditional waited 0ms 0ms 0ms 20ms
Direct full conditional waited 0 0 0 0
KSwapd number congest waited 2106 2308 2116 1915
KSwapd time congest waited 139924ms 157832ms 125652ms 132516ms
KSwapd full congest waited 1346 1530 1202 1278
KSwapd number conditional waited 12922 16320 10943 14670
KSwapd time conditional waited 0ms 0ms 0ms 0ms
KSwapd full conditional waited 0 0 0 0
Reclaim statistics are not radically changed. The stall times in kswapd
are massive but it is clear that it is due to calls to congestion_wait()
and that is almost certainly the call in balance_pgdat(). Otherwise
stalls due to dirty pages are non-existant.
I ran a benchmark that stressed high-order allocation. This is very
artifical load but was used in the past to evaluate lumpy reclaim and
compaction. Generally I look at allocation success rates and latency
figures.
STRESS-HIGHALLOC
3.3.0-vanilla rc2-vanilla lumpyremove-v2r3 nosync-v2r3
Pass 1 81.00 ( 0.00%) 28.00 (-53.00%) 24.00 (-57.00%) 28.00 (-53.00%)
Pass 2 82.00 ( 0.00%) 39.00 (-43.00%) 38.00 (-44.00%) 43.00 (-39.00%)
while Rested 88.00 ( 0.00%) 87.00 (-1.00%) 88.00 ( 0.00%) 88.00 ( 0.00%)
MMTests Statistics: duration
Sys Time Running Test (seconds) 740.93 681.42 685.14 684.87
User+Sys Time Running Test (seconds) 2922.65 3269.52 3281.35 3279.44
Total Elapsed Time (seconds) 1161.73 1152.49 1159.55 1161.44
MMTests Statistics: vmstat
Page Ins 4486020 2807256 2855944 2876244
Page Outs 7261600 7973688 7975320 7986120
Swap Ins 31694 0 0 0
Swap Outs 98179 0 0 0
Direct pages scanned 53494 57731 34406 113015
Kswapd pages scanned 6271173 1287481 1278174 1219095
Kswapd pages reclaimed 2029240 1281025 1260708 1201583
Direct pages reclaimed 1468 14564 16649 92456
Kswapd efficiency 32% 99% 98% 98%
Kswapd velocity 5398.133 1117.130 1102.302 1049.641
Direct efficiency 2% 25% 48% 81%
Direct velocity 46.047 50.092 29.672 97.306
Percentage direct scans 0% 4% 2% 8%
Page writes by reclaim 1616049 0 0 0
Page writes file 1517870 0 0 0
Page writes anon 98179 0 0 0
Page reclaim immediate 103778 27339 9796 17831
Page rescued immediate 0 0 0 0
Slabs scanned 1096704 986112 980992 998400
Direct inode steals 223 215040 216736 247881
Kswapd inode steals 175331 61548 68444 63066
Kswapd skipped wait 21991 0 1 0
THP fault alloc 1 135 125 134
THP collapse alloc 393 311 228 236
THP splits 25 13 7 8
THP fault fallback 0 0 0 0
THP collapse fail 3 5 7 7
Compaction stalls 865 1270 1422 1518
Compaction success 370 401 353 383
Compaction failures 495 869 1069 1135
Compaction pages moved 870155 3828868 4036106 4423626
Compaction move failure 26429 23865 29742 27514
Success rates are completely hosed for 3.4-rc2 which is almost certainly
due to commit fe2c2a1066 ("vmscan: reclaim at order 0 when compaction
is enabled"). I expected this would happen for kswapd and impair
allocation success rates (https://lkml.org/lkml/2012/1/25/166) but I did
not anticipate this much a difference: 80% less scanning, 37% less
reclaim by kswapd
In comparison, reclaim/compaction is not aggressive and gives up easily
which is the intended behaviour. hugetlbfs uses __GFP_REPEAT and would
be much more aggressive about reclaim/compaction than THP allocations
are. The stress test above is allocating like neither THP or hugetlbfs
but is much closer to THP.
Mainline is now impaired in terms of high order allocation under heavy
load although I do not know to what degree as I did not test with
__GFP_REPEAT. Keep this in mind for bugs related to hugepage pool
resizing, THP allocation and high order atomic allocation failures from
network devices.
In terms of congestion throttling, I see the following for this test
FTrace Reclaim Statistics: congestion_wait
Direct number congest waited 3 0 0 0
Direct time congest waited 0ms 0ms 0ms 0ms
Direct full congest waited 0 0 0 0
Direct number conditional waited 957 512 1081 1075
Direct time conditional waited 0ms 0ms 0ms 0ms
Direct full conditional waited 0 0 0 0
KSwapd number congest waited 36 4 3 5
KSwapd time congest waited 3148ms 400ms 300ms 500ms
KSwapd full congest waited 30 4 3 5
KSwapd number conditional waited 88514 197 332 542
KSwapd time conditional waited 4980ms 0ms 0ms 0ms
KSwapd full conditional waited 49 0 0 0
The "conditional waited" times are the most interesting as this is
directly impacted by the number of dirty pages encountered during scan.
As lumpy reclaim is no longer scanning contiguous ranges, it is finding
fewer dirty pages. This brings wait times from about 5 seconds to 0.
kswapd itself is still calling congestion_wait() so it'll still stall but
it's a lot less.
In terms of the type of IO we were doing, I see this
FTrace Reclaim Statistics: mm_vmscan_writepage
Direct writes anon sync 0 0 0 0
Direct writes anon async 0 0 0 0
Direct writes file sync 0 0 0 0
Direct writes file async 0 0 0 0
Direct writes mixed sync 0 0 0 0
Direct writes mixed async 0 0 0 0
KSwapd writes anon sync 0 0 0 0
KSwapd writes anon async 91682 0 0 0
KSwapd writes file sync 0 0 0 0
KSwapd writes file async 822629 0 0 0
KSwapd writes mixed sync 0 0 0 0
KSwapd writes mixed async 0 0 0 0
In 3.2, kswapd was doing a bunch of async writes of pages but
reclaim/compaction was never reaching a point where it was doing sync
IO. This does not guarantee that reclaim/compaction was not calling
wait_on_page_writeback() but I would consider it unlikely. It indicates
that merging patches 2 and 3 to stop reclaim/compaction calling
wait_on_page_writeback() should be safe.
This patch:
Lumpy reclaim had a purpose but in the mind of some, it was to kick the
system so hard it trashed. For others the purpose was to complicate
vmscan.c. Over time it was giving softer shoes and a nicer attitude but
memory compaction needs to step up and replace it so this patch sends
lumpy reclaim to the farm.
The tracepoint format changes for isolating LRU pages with this patch
applied. Furthermore reclaim/compaction can no longer queue dirty pages
in pageout() if the underlying BDI is congested. Lumpy reclaim used
this logic and reclaim/compaction was using it in error.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Konstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ying Han <yinghan@google.com>
Cc: Andy Whitcroft <apw@shadowen.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The swap token code no longer fits in with the current VM model. It
does not play well with cgroups or the better NUMA placement code in
development, since we have only one swap token globally.
It also has the potential to mess with scalability of the system, by
increasing the number of non-reclaimable pages on the active and
inactive anon LRU lists.
Last but not least, the swap token code has been broken for a year
without complaints, as reported by Konstantin Khlebnikov. This suggests
we no longer have much use for it.
The days of sub-1G memory systems with heavy use of swap are over. If
we ever need thrashing reducing code in the future, we will have to
implement something that does scale.
Signed-off-by: Rik van Riel <riel@redhat.com>
Cc: Konstantin Khlebnikov <khlebnikov@openvz.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Hugh Dickins <hughd@google.com>
Acked-by: Bob Picco <bpicco@meloft.net>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
If journal superblock is written only in disk's caches and other transaction
starts reusing space of the transaction cleaned from the log, it can happen
blocks of a new transaction reach the disk before journal superblock. When
power failure happens in such case, subsequent journal replay would still try
to replay the old transaction but some of it's blocks may be already
overwritten by the new transaction. For this reason we must use WRITE_FUA when
updating log tail and we must first write new log tail to disk and update
in-memory information only after that.
Signed-off-by: Jan Kara <jack@suse.cz>
There are three case of updating journal superblock. In the first case, we want
to mark journal as empty (setting s_sequence to 0), in the second case we want
to update log tail, in the third case we want to update s_errno. Split these
cases into separate functions. It makes the code slightly more straightforward
and later patches will make the distinction even more important.
Signed-off-by: Jan Kara <jack@suse.cz>
The current RCU_FAST_NO_HZ assumes that timers do not migrate unless a
CPU goes offline, in which case it assumes that the CPU will have to come
out of dyntick-idle mode (cancelling the timer) in order to go offline.
This is important because when RCU_FAST_NO_HZ permits a CPU to enter
dyntick-idle mode despite having RCU callbacks pending, it posts a timer
on that CPU to force a wakeup on that CPU. This wakeup ensures that the
CPU will eventually handle the end of the grace period, including invoking
its RCU callbacks.
However, Pascal Chapperon's test setup shows that the timer handler
rcu_idle_gp_timer_func() really does get invoked in some cases. This is
problematic because this can cause the CPU that entered dyntick-idle
mode despite still having RCU callbacks pending to remain in
dyntick-idle mode indefinitely, which means that its RCU callbacks might
never be invoked. This situation can result in grace-period delays or
even system hangs, which matches Pascal's observations of slow boot-up
and shutdown (https://lkml.org/lkml/2012/4/5/142). See also the bugzilla:
https://bugzilla.redhat.com/show_bug.cgi?id=806548
This commit therefore causes the "should never be invoked" timer handler
rcu_idle_gp_timer_func() to use smp_call_function_single() to wake up
the CPU for which the timer was intended, allowing that CPU to invoke
its RCU callbacks in a timely manner.
Reported-by: Pascal Chapperon <pascal.chapperon@wanadoo.fr>
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
When writeback_single_inode() is called on inode which has I_SYNC already
set while doing WB_SYNC_NONE, inode is moved to b_more_io list. However
this makes sense only if the caller is flusher thread. For other callers of
writeback_single_inode() it doesn't really make sense and may be even wrong
- flusher thread may be doing WB_SYNC_ALL writeback in parallel.
So we move requeueing from writeback_single_inode() to writeback_sb_inodes().
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
Add tracepoints to wakeup_source_activate and wakeup_source_deactivate.
Useful for checking that specific wakeup sources overlap as expected.
Signed-off-by: Arve Hjønnevåg <arve@android.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Traces of rcu_prep_idle events can be confusing because
rcu_cleanup_after_idle() does no tracing. This commit therefore adds
this tracing.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Fixes the following build warning on x86_64.
In file included from include/trace/ftrace.h:567:0,
from include/trace/define_trace.h:86,
from include/trace/events/asoc.h:410,
from sound/soc/soc-core.c:45:
include/trace/events/asoc.h: In function 'ftrace_raw_event_snd_soc_dapm_output_path':
include/trace/events/asoc.h:246:1: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
include/trace/events/asoc.h: In function 'ftrace_raw_event_snd_soc_dapm_input_path':
include/trace/events/asoc.h:275:1: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
Signed-off-by: Liam Girdwood <lrg@ti.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
In preparation for ASoC DSP support.
Add a DAPM API call to determine whether a DAPM audio path is valid between
source and sink widgets. This also takes into account all kcontrol mux and mixer
settings in between the source and sink widgets to validate the audio path.
This will be used by the DSP core to determine the runtime DAI mappings
between FE and BE DAIs in order to run PCM operations.
Signed-off-by: Liam Girdwood <lrg@ti.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Currently we write out all journal buffers in WRITE_SYNC mode. This improves
performance for fsync heavy workloads but hinders performance when writes
are mostly asynchronous, most noticably it slows down readers and users
complain about slow desktop response etc.
So submit writes as asynchronous in the normal case and only submit writes as
WRITE_SYNC if we detect someone is waiting for current transaction commit.
I've gathered some numbers to back this change. The first is the read latency
test. It measures time to read 1 MB after several seconds of sleeping in
presence of streaming writes.
Top 10 times (out of 90) in us:
Before After
2131586 697473
1709932 557487
1564598 535642
1480462 347573
1478579 323153
1408496 222181
1388960 181273
1329565 181070
1252486 172832
1223265 172278
Average:
619377 82180
So the improvement in both maximum and average latency is massive.
I've measured fsync throughput by:
fs_mark -n 100 -t 1 -s 16384 -d /mnt/fsync/ -S 1 -L 4
in presence of streaming reader. The numbers (fsyncs/s) are:
Before After
9.9 6.3
6.8 6.0
6.3 6.2
5.8 6.1
So fsync performance seems unharmed by this change.
Signed-off-by: Jan Kara <jack@suse.cz>
workqueue_execute_end() is called after the callback function,
not before.
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
1. TRACE_EVENT(sched_process_exec) forgets to actually use the
old pid argument, it sets ->old_pid = p->pid.
2. search_binary_handler() uses the wrong pid number. tracepoint
needs the global pid_t from the root namespace, while old_pid
is the virtual pid number as it seen by the tracer/parent.
With this patch we have two pid_t's in search_binary_handler(),
not really nice. Perhaps we should switch to "struct pid*", but
in this case it would be better to cleanup the current code
first and move the "depth == 0" code outside.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: David Smith <dsmith@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Link: http://lkml.kernel.org/r/20120330162636.GA4857@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The <linux/device.h> header includes a lot of stuff, and
it in turn gets a lot of use just for the basic "struct device"
which appears so often.
Clean up the users as follows:
1) For those headers only needing "struct device" as a pointer
in fcn args, replace the include with exactly that.
2) For headers not really using anything from device.h, simply
delete the include altogether.
3) For headers relying on getting device.h implicitly before
being included themselves, now explicitly include device.h
4) For files in which doing #1 or #2 uncovers an implicit
dependency on some other header, fix by explicitly adding
the required header(s).
Any C files that were implicitly relying on device.h to be
present have already been dealt with in advance.
Total removals from #1 and #2: 51. Total additions coming
from #3: 9. Total other implicit dependencies from #4: 7.
As of 3.3-rc1, there were 110, so a net removal of 42 gives
about a 38% reduction in device.h presence in include/*
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
When we reach jbd2_cleanup_journal_tail(), there is no guarantee that
checkpointed buffers are on a stable storage - especially if buffers were
written out by jbd2_log_do_checkpoint(), they are likely to be only in disk's
caches. Thus when we update journal superblock effectively removing old
transaction from journal, this write of superblock can get to stable storage
before those checkpointed buffers which can result in filesystem corruption
after a crash. Thus we must unconditionally issue a cache flush before we
update journal superblock in these cases.
A similar problem can also occur if journal superblock is written only in
disk's caches, other transaction starts reusing space of the transaction
cleaned from the log and power failure happens. Subsequent journal replay would
still try to replay the old transaction but some of it's blocks may be already
overwritten by the new transaction. For this reason we must use WRITE_FUA when
updating log tail and we must first write new log tail to disk and update
in-memory information only after that.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
There are three case of updating journal superblock. In the first case, we want
to mark journal as empty (setting s_sequence to 0), in the second case we want
to update log tail, in the third case we want to update s_errno. Split these
cases into separate functions. It makes the code slightly more straightforward
and later patches will make the distinction even more important.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Added a minimal exec tracepoint. Exec is an important major event
in the life of a task, like fork(), clone() or exit(), all of
which we already trace.
[ We also do scheduling re-balancing during exec() - so it's useful
from a scheduler instrumentation POV as well. ]
If you want to watch a task start up, when it gets exec'ed is a good place
to start. With the addition of this tracepoint, exec's can be monitored
and better picture of general system activity can be obtained. This
tracepoint will also enable better process life tracking, allowing you to
answer questions like "what process keeps starting up binary X?".
This tracepoint can also be useful in ftrace filtering and trigger
conditions: i.e. starting or stopping filtering when exec is called.
Signed-off-by: David Smith <dsmith@redhat.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/4F314D19.7030504@redhat.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Commit 1ac9bc69 ("sched/tracing: Add a new tracepoint for sleeptime")
added a new sched:sched_stat_sleeptime tracepoint.
It's broken: the first sample we get on a task might be bad because
of a stale sleep_start value that wasn't reset at the last task switch
because the tracepoint was not active.
It also breaks the existing schedstat samples due to the side
effects of:
- se->statistics.sleep_start = 0;
...
- se->statistics.block_start = 0;
Nor do I see means to fix it without adding overhead to the scheduler
fast path, which I'm not willing to for the sake of redundant
instrumentation.
Most importantly, sleep time information can already be constructed
by tracing context switches and wakeups, and taking the timestamp
difference between the schedule-out, the wakeup and the schedule-in.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Andrew Vagin <avagin@openvz.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/n/tip-pc4c9qhl8q6vg3bs4j6k0rbd@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
When CONFIG_RCU_FAST_NO_HZ is enabled, RCU will allow a given CPU to
enter dyntick-idle mode even if it still has RCU callbacks queued.
RCU avoids system hangs in this case by scheduling a timer for several
jiffies in the future. However, if all of the callbacks on that CPU
are from kfree_rcu(), there is no reason to wake the CPU up, as it is
not a problem to defer freeing of memory.
This commit therefore tracks the number of callbacks on a given CPU
that are from kfree_rcu(), and avoids scheduling the timer if all of
a given CPU's callbacks are from kfree_rcu().
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This patch adds trace_jbd2_drop_transaction and
trace_jbd2_update_superblock_end because there are similar tracepoints
in jbd and they are needed in jbd2 as well.
Reviewed-by: Lukas Czerner <lczerner@redhat.com>
Signed-off-by: Seiji Aguchi <seiji.aguchi@hds.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Add a printk.console trace point to record any printk
messages into the trace, regardless of the current
console loglevel. This can help correlate (existing)
printk debugging with other tracing.
Link: http://lkml.kernel.org/r/1322161388.5366.54.camel@jlt3.sipsolutions.net
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The power and cpuidle tracepoints are called within a rcu_idle_exit()
section, and must be denoted with the _rcuidle() version of the tracepoint.
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This patch adds three trace points to the status routines
in the sunrpc state machine.
The goal of these trace points is to give an Admin
the ability to check on binding status or connection
status to see if there is a potential problem.
Signed-off-by: Steve Dickson <steved@redhat.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
The reporting of the RPC queue name needs to use the __string()
event interface.
Reported-by: Neil Horman <nhorman@redhat.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
When a SD card is hot removed without umount, del_gendisk() will call
bdi_unregister() without destroying/freeing it. This leaves the bdi in
the bdi->dev = NULL, bdi->wb.task = NULL, bdi->bdi_list removed state.
When sync(2) gets the bdi before bdi_unregister() and calls
bdi_queue_work() after the unregister, trace_writeback_queue will be
dereferencing the NULL bdi->dev. Fix it with a simple test for NULL.
LKML-reference: http://lkml.org/lkml/2012/1/18/346
Cc: stable@kernel.org
Reported-by: Rabin Vincent <rabin@rab.in>
Tested-by: Namjae Jeon <linkinjeon@gmail.com>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
The code is not going to be removed, so remove the comment stating
that it will be.
Signed-off-by: Jesper Juhl <jj@chaosbits.net>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
bdi_prune_sb() resets sb->s_bdi to default_backing_dev_info when the
tearing down the original bdi. Fix trace_writeback_single_inode to
use sb->s_bdi=default_backing_dev_info rather than bdi->dev=NULL for a
teared down bdi.
Cc: <stable@kernel.org>
Reported-by: Rabin Vincent <rabin@rab.in>
Tested-by: Rabin Vincent <rabin@rab.in>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
This in addition to a script in my btrfs-tracing tree will help track down space
leaks when we're getting space left over in block groups on umount. Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>
I used these tracepoints when figuring out what the cluster stuff was doing, so
add them to mainline in case we need to profile this stuff again. Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>
__send_signal()->trace_signal_generate() doesn't report enough info.
The users want to know was the signal actually delivered or not, and
they also need the shared/private info.
The patch moves trace_signal_generate() at the end of __send_signal()
and adds the 2 additional arguments.
This also allows us to kill trace_signal_overflow_fail/lose_info, we
can simply add the appropriate TRACE_SIGNAL_ "result" codes.
Reported-by: Seiji Aguchi <saguchi@redhat.com>
Reviewed-by: Seiji Aguchi <seiji.aguchi@hds.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
In trace_mm_vmscan_lru_isolate(), we don't output 'file' information to
the trace event and it is a bit inconvenient for the user to get the
real information(like pasted below). mm_vmscan_lru_isolate:
isolate_mode=2 order=0 nr_requested=32 nr_scanned=32 nr_taken=32
contig_taken=0 contig_dirty=0 contig_failed=0
'active' can be obtained by analyzing mode(Thanks go to Minchan and
Mel), So this patch adds 'file' to the trace event and it now looks
like: mm_vmscan_lru_isolate: isolate_mode=2 order=0 nr_requested=32
nr_scanned=32 nr_taken=32 contig_taken=0 contig_dirty=0 contig_failed=0
file=0
Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Reviewed-by: Minchan Kim <minchan@kernel.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
oom_score_adj is used for guarding processes from OOM-Killer. One of
problem is that it's inherited at fork(). When a daemon set oom_score_adj
and make children, it's hard to know where the value is set.
This patch adds some tracepoints useful for debugging. This patch adds
3 trace points.
- creating new task
- renaming a task (exec)
- set oom_score_adj
To debug, users need to enable some trace pointer. Maybe filtering is useful as
# EVENT=/sys/kernel/debug/tracing/events/task/
# echo "oom_score_adj != 0" > $EVENT/task_newtask/filter
# echo "oom_score_adj != 0" > $EVENT/task_rename/filter
# echo 1 > $EVENT/enable
# EVENT=/sys/kernel/debug/tracing/events/oom/
# echo 1 > $EVENT/enable
output will be like this.
# grep oom /sys/kernel/debug/tracing/trace
bash-7699 [007] d..3 5140.744510: oom_score_adj_update: pid=7699 comm=bash oom_score_adj=-1000
bash-7699 [007] ...1 5151.818022: task_newtask: pid=7729 comm=bash clone_flags=1200011 oom_score_adj=-1000
ls-7729 [003] ...2 5151.818504: task_rename: pid=7729 oldcomm=bash newcomm=ls oom_score_adj=-1000
bash-7699 [002] ...1 5175.701468: task_newtask: pid=7730 comm=bash clone_flags=1200011 oom_score_adj=-1000
grep-7730 [007] ...2 5175.701993: task_rename: pid=7730 oldcomm=bash newcomm=grep oom_score_adj=-1000
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Rename mm_page_free_direct into mm_page_free and mm_pagevec_free into
mm_page_free_batched
Since v2.6.33-5426-gc475dab the kernel triggers mm_page_free_direct for
all freed pages, not only for directly freed. So, let's name it properly.
For pages freed via page-list we also trigger mm_page_free_batched event.
Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
If CONFIG_SCHEDSTATS is defined, the kernel maintains
information about how long the task was sleeping or
in the case of iowait, blocking in the kernel before
getting woken up.
This will be useful for sleep time profiling.
Note: this information is only provided for sched_fair.
Other scheduling classes may choose to provide this in
the future.
Note: the delay includes the time spent on the runqueue
as well.
Signed-off-by: Arun Sharma <asharma@fb.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
Cc: Andrew Vagin <avagin@openvz.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/1324512940-32060-2-git-send-email-asharma@fb.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
pa_inode in group_pa is set NULL in ext4_mb_new_group_pa, so
pa_inode should be not referenced.
Reported-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Yongqiang Yang <xiaoqiangnk@gmail.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Compensate the task's think time when computing the final pause time,
so that ->dirty_ratelimit can be executed accurately.
think time := time spend outside of balance_dirty_pages()
In the rare case that the task slept longer than the 200ms period time
(result in negative pause time), the sleep time will be compensated in
the following periods, too, if it's less than 1 second.
Accumulated errors are carefully avoided as long as the max pause area
is not hitted.
Pseudo code:
period = pages_dirtied / task_ratelimit;
think = jiffies - dirty_paused_when;
pause = period - think;
1) normal case: period > think
pause = period - think
dirty_paused_when = jiffies + pause
nr_dirtied = 0
period time
|===============================>|
think time pause time
|===============>|==============>|
------|----------------|---------------|------------------------
dirty_paused_when jiffies
2) no pause case: period <= think
don't pause; reduce future pause time by:
dirty_paused_when += period
nr_dirtied = 0
period time
|===============================>|
think time
|===================================================>|
------|--------------------------------+-------------------|----
dirty_paused_when jiffies
Acked-by: Jan Kara <jack@suse.cz>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
This makes the binary trace understandable by trace-cmd.
CC: Dave Chinner <david@fromorbit.com>
CC: Curt Wohlgemuth <curtw@google.com>
CC: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
The current rcu_batch_end event trace records only the name of the RCU
flavor and the total number of callbacks that remain queued on the
current CPU. This is insufficient for testing and tuning the new
dyntick-idle RCU_FAST_NO_HZ code, so this commit adds idle state along
with whether or not any of the callbacks that were ready to invoke
at the beginning of rcu_do_batch() are still queued.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
The current implementation of RCU_FAST_NO_HZ prevents CPUs from entering
dyntick-idle state if they have RCU callbacks pending. Unfortunately,
this has the side-effect of often preventing them from entering this
state, especially if at least one other CPU is not in dyntick-idle state.
However, the resulting per-tick wakeup is wasteful in many cases: if the
CPU has already fully responded to the current RCU grace period, there
will be nothing for it to do until this grace period ends, which will
frequently take several jiffies.
This commit therefore permits a CPU that has done everything that the
current grace period has asked of it (rcu_pending() == 0) even if it
still as RCU callbacks pending. However, such a CPU posts a timer to
wake it up several jiffies later (6 jiffies, based on experience with
grace-period lengths). This wakeup is required to handle situations
that can result in all CPUs being in dyntick-idle mode, thus failing
to ever complete the current grace period. If a CPU wakes up before
the timer goes off, then it cancels that timer, thus avoiding spurious
wakeups.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
With the new implementation of RCU_FAST_NO_HZ, it was possible to hang
RCU grace periods as follows:
o CPU 0 attempts to go idle, cycles several times through the
rcu_prepare_for_idle() loop, then goes dyntick-idle when
RCU needs nothing more from it, while still having at least
on RCU callback pending.
o CPU 1 goes idle with no callbacks.
Both CPUs can then stay in dyntick-idle mode indefinitely, preventing
the RCU grace period from ever completing, possibly hanging the system.
This commit therefore prevents CPUs that have RCU callbacks from entering
dyntick-idle mode. This approach also eliminates the need for the
end-of-grace-period IPIs used previously.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit adds trace_rcu_prep_idle(), which is invoked from
rcu_prepare_for_idle() and rcu_wake_cpu() to trace attempts on
the part of RCU to force CPUs into dyntick-idle mode.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit updates the trace_rcu_dyntick() header comment to reflect
events added by commit 4b4f421.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Mel Gorman