* [xfs] f876e446: +1.2% fileio.requests_per_sec
@ 2014-03-03 14:21 Fengguang Wu
2014-03-03 23:17 ` Dave Chinner
0 siblings, 1 reply; 2+ messages in thread
From: Fengguang Wu @ 2014-03-03 14:21 UTC (permalink / raw)
To: Dave Chinner; +Cc: linux-fsdevel, LKML
Hi Dave,
We noticed the below changes on commit f876e44603ad091c840a5fae5b0753bbb421c037
("xfs: always do log forces via the workqueue"):
Basically there are +1.2% increased throughput with +29.5% increased
context switches.
test box: NHM
test case: fileio rndwr-sync
v3.14-rc1 f876e44603ad091c840a5fae5
--------------- -------------------------
192 ~ 0% +1.2% 194 ~ 0% TOTAL fileio.requests_per_sec
2 ~25% +47.4% 4 ~ 0% TOTAL time.percent_of_cpu_this_job_got
1907 ~16% +29.5% 2471 ~ 0% TOTAL vmstat.system.cs
331131 ~ 0% +10.9% 367298 ~ 0% TOTAL time.voluntary_context_switches
3255 ~ 0% +2330.6% 79126 ~ 0% TOTAL time.involuntary_context_switches
3703982 ~ 0% +1.2% 3747974 ~ 0% TOTAL time.file_system_outputs
35.04 ~20% +9.8% 38.48 ~ 0% TOTAL iostat.sda.wrqm/s
time.voluntary_context_switches
380000 ++----------------------------------------------------------------+
360000 O+ O O O O O O O O O O O O O O O O O O O O O O O
| |
340000 *+.*..*..*.*..*..*..*..*..*..*..* *..*..*..*..*..*..*.* |
320000 ++ : : |
| : : |
300000 ++ : : |
280000 ++ : : |
260000 ++ : : |
| : : |
240000 ++ : : |
220000 ++ :: |
| : |
200000 ++ * |
180000 ++----------------------------------------------------------------+
time.involuntary_context_switches
80000 ++------------------------O--O--O--O-----O--O--O--O-O--O--O--O--O--O
O O O O O O O O O O |
70000 ++ |
60000 ++ |
| |
50000 ++ |
| |
40000 ++ |
| |
30000 ++ |
20000 ++ |
| |
10000 ++ |
*..*..*..*..*..*.*..*..*..*..*..*..*..*..*..*..*..*.*..*..* |
0 ++-----------------------------------------------------------------+
Thanks,
Fengguang
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [xfs] f876e446: +1.2% fileio.requests_per_sec
2014-03-03 14:21 [xfs] f876e446: +1.2% fileio.requests_per_sec Fengguang Wu
@ 2014-03-03 23:17 ` Dave Chinner
0 siblings, 0 replies; 2+ messages in thread
From: Dave Chinner @ 2014-03-03 23:17 UTC (permalink / raw)
To: Fengguang Wu; +Cc: Dave Chinner, linux-fsdevel, LKML
On Mon, Mar 03, 2014 at 10:21:51PM +0800, Fengguang Wu wrote:
> Hi Dave,
>
> We noticed the below changes on commit f876e44603ad091c840a5fae5b0753bbb421c037
> ("xfs: always do log forces via the workqueue"):
>
> Basically there are +1.2% increased throughput with +29.5% increased
> context switches.
Yes, the increase in context switches is expected. Every sync IO
causes a log force if it changed inode metadata, and the above
commit, as it describes, moves them to a work queue. Hence there's
more context switches involved in a log force that has to do work.
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
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