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Message-ID: <20100729145632.GC25863@redhat.com> Date: Thu, 29 Jul 2010 10:56:32 -0400 From: Vivek Goyal <vgoyal@...hat.com> To: Christoph Hellwig <hch@...radead.org> Cc: Heinz Diehl <htd@...cy-poultry.org>, linux-kernel@...r.kernel.org, jaxboe@...ionio.com, nauman@...gle.com, dpshah@...gle.com, guijianfeng@...fujitsu.com, jmoyer@...hat.com, czoccolo@...il.com, "Ted Ts'o" <tytso@....edu> Subject: Re: cfq fsync patch testing results (Was: Re: [RFC PATCH] cfq-iosched: IOPS mode for group scheduling and new group_idle tunable) On Thu, Jul 29, 2010 at 12:34:43AM -0400, Vivek Goyal wrote: > 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. For the sake of completeness, I also ran same tests on ext3 with barrier enabled. ext3 (barrier=1) ext3 (barrier=1) fsync time: 2.7601 fsync time: 1.5323 fsync time: 2.2352 fsync time: 1.5254 fsync time: 2.1689 fsync time: 1.4228 fsync time: 2.1666 fsync time: 1.8404 fsync time: 2.3017 fsync time: 5.6249 fsync time: 2.2256 fsync time: 1.6099 fsync time: 2.1588 fsync time: 1.5318 fsync time: 5.1648 fsync time: 2.0092 fsync time: 5.8390 fsync time: 1.9966 fsync time: 0.2109 fsync time: 2.0055 fsync time: 0.0906 fsync time: 2.0054 fsync time: 3.6327 fsync time: 0.1778 fsync time: 3.0161 fsync time: 0.0827 fsync time: 2.3194 fsync time: 2.3796 fsync time: 2.0581 fsync time: 1.5960 fsync time: 2.2850 fsync time: 1.5074 fsync time: 2.2002 fsync time: 1.8653 fsync time: 2.1932 fsync time: 1.8910 fsync time: 2.1753 fsync time: 1.9091 fsync time: 2.1669 fsync time: 1.8322 fsync time: 2.1671 fsync time: 1.8744 fsync time: 1.9552 fsync time: 1.8254 fsync time: 3.9870 fsync time: 1.8662 fsync time: 2.5140 fsync time: 1.8587 fsync time: 0.0867 fsync time: 1.7981 It is hard to say whether things improved or not with patch. I guess slight improvement is there. What is interesting though that this fsync-tester test case works well with ext3 and xfs but with ext4 there seems to be large spikes in fsync times. [CCing Ted Tso] Thanks Vivek -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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