Messages in this thread | | | Date | Thu, 29 Jul 2010 00:34:43 -0400 | From | Vivek Goyal <> | Subject | cfq fsync patch testing results (Was: Re: [RFC PATCH] cfq-iosched: IOPS mode for group scheduling and new group_idle tunable) |
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On Wed, Jul 28, 2010 at 07:57:16PM -0400, Christoph Hellwig wrote: > On Wed, Jul 28, 2010 at 04:22:12PM -0400, Vivek Goyal wrote: > > I also did "time firefox &" testing to see how long firefox takes to > > launch when linus torture test is running and without patch it took > > around 20 seconds and with patch it took around 17 seconds. > > > > So to me above test results suggest that this patch does not worsen > > the performance. In fact it helps. (at least on ext3 file system.) > > > > Not sure why are you seeing different results with XFS. > > So why didn't you test it with XFS to verify his results?
Just got little lazy. Find the testing results with ext3, ext4 and xfs below.
> We all know > that different filesystems have different I/O patters, and we have > a history of really nasty regressions in one filesystem by good meaning > changes to the I/O scheduler. > > ext3 in fact is a particularly bad test case as it not only doesn't have > I/O barriers enabled, but also has particularly bad I/O patterns > compared to modern filesystems.
Ext3 results ============ ext3 (2.6.35-rc6) ext3 (35-rc6-fsync) ----------------- ------------------- fsync time: 3.4173 fsync time: 0.0171 fsync time: 0.8831 fsync time: 0.0951 fsync time: 0.6985 fsync time: 0.0848 fsync time: 8.9449 fsync time: 0.1206 fsync time: 4.3075 fsync time: 0.4150 fsync time: 6.0146 fsync time: 0.0856 fsync time: 9.7134 fsync time: 0.1151 fsync time: 9.2247 fsync time: 0.1083 fsync time: 6.5061 fsync time: 0.1218 fsync time: 6.1862 fsync time: 4.1666 fsync time: 6.1136 fsync time: 0.1075 fsync time: 3.3593 fsync time: 0.3442 fsync time: 4.3309 fsync time: 0.1062 fsync time: 2.3596 fsync time: 2.8502 fsync time: 0.0151 fsync time: 0.0433 fsync time: 0.0180 fsync time: 4.0526 fsync time: 0.3685 fsync time: 0.1819 fsync time: 2.7396 fsync time: 0.1479 fsync time: 3.1537 fsync time: 0.1480 fsync time: 2.4474 fsync time: 0.1715 fsync time: 2.7085 fsync time: 0.0079 fsync time: 3.1629 fsync time: 0.0181 fsync time: 2.9186 fsync time: 0.0134
XFS results ========== XFS (2.6.35-rc6) XFS (with fsync patch) fsync time: 5.0746 fsync time: 1.8025 fsync time: 3.0057 fsync time: 2.3392 fsync time: 3.0960 fsync time: 2.2810 fsync time: 2.8392 fsync time: 2.2894 fsync time: 2.4901 fsync time: 2.3059 fsync time: 2.3151 fsync time: 2.3061 fsync time: 2.3066 fsync time: 2.9825 fsync time: 0.6608 fsync time: 2.3144 fsync time: 0.0595 fsync time: 2.2894 fsync time: 2.0977 fsync time: 0.0508 fsync time: 2.3236 fsync time: 2.3396 fsync time: 2.3229 fsync time: 2.3310 fsync time: 2.3065 fsync time: 2.3061 fsync time: 2.3234 fsync time: 2.3060 fsync time: 2.3150 fsync time: 2.3561 fsync time: 2.3149 fsync time: 2.3313 fsync time: 2.3234 fsync time: 2.0221 fsync time: 2.3066 fsync time: 2.2891 fsync time: 2.3232 fsync time: 2.3144 fsync time: 2.3317 fsync time: 2.3144 fsync time: 2.3321 fsync time: 2.2894 fsync time: 2.3232 fsync time: 2.3228 fsync time: 0.0514 fsync time: 2.3144 fsync time: 2.2480 fsync time: 0.0506
Ext4 ==== ext4 (vanilla) ext4 (patched) fsync time: 3.4080 fsync time: 2.9109 fsync time: 17.8330 fsync time: 25.0503 fsync time: 0.0922 fsync time: 2.5495 fsync time: 0.0710 fsync time: 0.0943 fsync time: 19.7977 fsync time: 0.0770 fsync time: 20.6592 fsync time: 16.3287 fsync time: 0.1020 fsync time: 24.4983 fsync time: 0.0689 fsync time: 0.1006 fsync time: 19.9981 fsync time: 0.0783 fsync time: 20.6605 fsync time: 19.1181 fsync time: 0.0930 fsync time: 22.0860 fsync time: 0.0776 fsync time: 0.0909
Notes: ====== - Above results are with and without corrado's fsync issue patch. We happen to be discussing it in a different thread though, hence specifying it specifically.
- I am running linus torture test and also running ted so's fsync-tester to monitor fsync latencies.
- Looks like ext3 fsync times have improved. - XFS fsync times have remained unchanged. - ext4 fsync times seems to have gone up a bit.
I used default mount options. So I am assuming high fsync times of ext4 comes from the fact that barriers much be enabled by default. Will do some blktracing on ext4 case tomorrow, otherwise I think this patch looks good.
Thanks Vivek
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