Messages in this thread | | | Date | Sun, 24 Jun 2007 17:52:14 +0200 | From | Ingo Molnar <> | Subject | Re: [patch] CFS scheduler, -v18 |
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* Willy Tarreau <w@1wt.eu> wrote:
> Today I had a little time to try CFS again (last time it was -v9!). I > ran it on top of 2.6.20.14, and simply tried ocbench again. You > remember ? With -v9, I ran 64 processes which all progressed very > smoothly. With -v18, it's not the case anymore. When I run 64 > processes, only 7 of them show smooth rounds, while all the other ones > are only updated once a second. Sometimes they only progress by one > iteration, sometimes by a full round. Some are even updated once ever > 2 seconds, because if I drag an xterm above them and quickly remove > it, the xterm leaves a trace there for up to 2 seconds. > > Also, only one of my 2 CPUs is used. I see the rq vary between 1 and > 5, with a permanent 50% idle... : > > procs memory swap io system cpu > r b w swpd free buff cache si so bi bo in cs us sy id > 1 0 0 0 874400 7864 90436 0 0 0 0 279 2204 50 0 50 > 3 0 0 0 874408 7864 90436 0 0 0 0 273 2122 50 1 50 > 1 0 0 0 874408 7864 90436 0 0 0 0 253 1660 49 1 50 > 3 0 0 0 874408 7864 90436 0 0 0 0 252 1977 50 0 50 > 2 0 0 0 874408 7864 90436 0 0 0 0 253 2274 49 1 50 > 3 0 0 0 874408 7864 90436 0 0 0 0 252 1846 49 1 50 > 1 0 0 0 874408 7864 90436 0 0 0 0 339 1782 49 1 50 > > I have no idea about what version brought that unexpected behaviour, > but it's clearly something which needs to be tracked down.
hm, the two problems might be related. Could you try v17 perhaps? In v18 i have 'unified' all the sched.c's between the various kernel releases, maybe that brought in something unexpected on 2.6.20.14. (perhaps try v2.6.21.5 based cfs too?)
> My scheduler is at 250 Hz, and here are the values I found in > /proc/sys/kernel:
could you send me the file the cfs-debug-info.sh script produced. You can pick the script up from:
http://people.redhat.com/mingo/cfs-scheduler/tools/cfs-debug-info.sh
(i'd suggest to send it in private mail, output is large and detailed. If your kernel has no /proc/config.gz then please send me your .config file too.)
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