2.6.21 -> 2.6.22 & 2.6.23-rc8 performance regression

Denys
2007-09-30T15:22:40Z

P.S. It seems SLAB/SLUB doesn't make much difference, just seems SLUB use a
bit more some resources.
Still problem appearing with softirqd/0 or softirqd/1 taking a lot CPU (while
on 2.6.21 it never came up of the "top"), and doesn't matter - if NAPI on
e1000 disabled or enabled. Additionally disabling all disk operations doesn't
make any difference.

defaulthost ~ #mpstat 1
Linux 2.6.23-rc8-build-0017 (defaulthost) 09/30/07

21:20:29 CPU %user %nice %sys %iowait %irq %soft %steal
%idle intr/s
21:20:30 all 21.11 0.00 14.57 8.04 0.00 48.74 0.00
7.54 3632.00
21:20:31 all 23.38 0.00 12.94 10.95 0.00 52.74 0.00
0.00 1524.00
21:20:32 all 21.50 0.00 16.50 8.50 0.00 53.50 0.00
0.00 1473.00
21:20:33 all 22.39 0.00 14.93 4.98 0.50 53.23 0.00
3.98 1492.08
21:20:34 all 5.31 0.00 0.97 0.48 0.00 93.24 0.00
0.00 1351.96

On 2.6.21 it looks:

defaulthost ~ #mpstat 1
Linux 2.6.21-gentoo-r3-build-0015 (defaulthost) 09/30/07

18:21:50 CPU %user %nice %sys %iowait %irq %soft %steal
%idle intr/s
18:21:51 all 29.50 0.00 21.50 12.50 0.00 6.00 0.00
30.50 8416.00
18:21:52 all 26.00 0.00 19.00 12.50 0.50 7.00 0.00
35.00 8663.64
18:21:53 all 27.23 0.00 17.82 13.37 0.99 6.44 0.00
34.16 7828.71
18:21:54 all 26.13 0.00 16.08 18.59 0.00 7.04 0.00
32.16 8657.58
18:21:55 all 22.89 0.00 16.92 18.91 0.50 6.47 0.00
34.33 7957.43
18:21:56 all 28.14 0.00 21.61 17.59 0.50 6.03 0.00
26.13 8531.00