per-task delay accounting
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- v1 Latest8 patches 31 repliesIn review
Patches in v1 No applies recorded yet
| # | Subject and files | Size | Replies | Applied |
|---|---|---|---|---|
| 1/8 | SetupDocumentation/ include/ include/ +6 more | +183 | 2 replies | |
| 2/8 | Block I/O, swapin delaysinclude/ include/ kernel/ +2 more | +50 | 2 replies | |
| 3/8 | cpu delaysinclude/ kernel/ | +50 | 4 replies | |
| 4/8 | generic netlink utility functionsinclude/ | +20 | 0 replies | |
| 5/8 | generic netlink interface for delay accountinginclude/ include/ init/ +3 more | +474 | 5 replies | |
| 6/8 | virtual cpu run timeinclude/ kernel/ | +17 | 2 replies | |
| 7/8 | proc interface for block I/O delaysfs/ include/ kernel/ | +30 | 1 reply | |
| 8/8 | documentation, userspace utilityDocumentation/ | +484 | 0 replies |
Reviews trailers per patch
No Reviewed-by, Acked-by or Tested-by trailers for v1 yet.
Cover letter [Patch 0/8] per-task delay accounting
Andrew,
Could you please include the following delay accounting patches in -mm ?
The patches have gone through several iterations on lkml and numerous comments raised by reviewers have been addressed
- several netlink interface comments (Jamal)
- block I/O collection method (Arjan)
- block I/O delays export through /proc (Andi)
- performance issues (Greg) (just addressed, see below)
- GPL headers (Arjan)
Most of the descriptions of the patches are either in the patch itself or in the documentation patch at the end.
Thanks
--Shailabh
Patch series
delayacct-setup.patch
delayacct-blkio-swapin.patch
delayacct-schedstats.patch
genetlink-utils.patch
delayacct-genetlink.patch
delayacct-virtcpu.patch
delayacct-procfs.patch
delayacct-doc.patch
Results highlights
- No statistically significant performance degradation is seen in kernbench, hackbench and large OLTP benchmark when delay accounting is configured.
The overheads of configuring delay accounting, without enabling at boot time, are statistically negligible for hackbench and a large OLTP benchmark and negative (i.e. performance improves) in kernbench.
- Similar lack of degradation is seen in kernbench and hackbench even when delay accounting is enabled at boot.
No data could be collected for the large OLTP benchmark (efforts ongoing).
Legend
Base
Vanilla 2.6.16 kernel without any patches applied
+patch
Delay accounting configured
but not enabled at boot
+patch+enable
Delay accounting enabled at boot
but no stats read
Time Elapsed time, averaged over 10 runs
Stddev Standard deviation of elapsed times
Ovhd % difference of elapsed time with respect to base kernel
t-value Used to measure statistical significance
of difference of two mean values (in this case mean elapsed time). Low t-values indicate insignificant difference. The t-values here were calculated at 95% confidence interval using the tool at
http://www.polarismr.com/education/tools_stat_diff_means.html
Hackbench
---------
200 groups, using pipes
Elapsed time, in seconds, lower better
Ovhd Time Stddev Ovhd significant (t-value)
Base 0% 43.483 0.178 na
+patch 0.1% 43.517 0.265 No (0.337)
+patch+enable 0.3% 43.629 0.167 No (1.892)
Kernbench
---------
Average of 10 iterations
Elapsed time, in seconds, lower better
Ovhd Time Stddev Ovhd significant (t-value)
Base 0% 196.704 0.459 na
+patch -0.5% 195.812 0.477 Yes (4.261)
+patch+enable 0.02% 196.752 0.356 No (0.261)
Large OLTP benchmark
--------------------
An industry standard large database online transaction processing workload was run with delay accounting patches configured ON and OFF.
The performance degradation of delay accounting was about 0.2%, which was well within the normal range of variation between similar runs.
No runs were taken with delay accounting enabled at boot time.