reaim - 2.6.3-mm1 IO performance down.

From: cliff white
Date: Tue Feb 24 2004 - 19:22:07 EST




Running the reaim 'new_fserver' workload, we now see a performance drop
on 2.6.3-mm1, ext3 filesystem

Kernel JPM Max Users Percent change
inux-2.6.3 10347.87 172 0.0
2.6.3-rc3-mm1 9826.35 164 -5.07
2.6.3-mm1 8938.17 140 (run 1) -13.65
2.6.3-mm1 9100.39 136 (run 2)-12.08

I have done some comparions graphs here, with readprofile data:
http://developer.osdl.org/cliffw/reaim/compares/r_comp/2.6.3_vs_mm1_r1/index.html
http://developer.osdl.org/cliffw/reaim/compares/r_comp/2.6.3_vs_mm1_r2/index.html

The interesting graph is the bottom one on the page, comparing client
run-time to number of children. The -mm1 kernel has a spike in run time, becoming
very noticealbe around 60-80 lusers.

kernel Users JPM Run Time
linux-2.6.3 60 10327.87 34.16 seconds
2.6.3-mm1 60 8279.75 42.61 seconds

Linux-2.6.3 80 10275.23 45.78 seconds
2.6.3-mm1 80 7841.31 59.99 seconds


For the same test on the same machine, results from 2.6.2-rc1-mm2 and 2.6.2-rc3-mm1
were within 1.0% of the linux-2.6.2 runs. So this is new.

More data and tests if requested - are there some patch sets we should try reverting?
cliffw

--
The church is near, but the road is icy.
The bar is far, but i will walk carefully. - Russian proverb
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