On Mon, 2008-02-18 at 10:55 +0100, Peter Zijlstra wrote:
> This is my current queue for single RQ group scheduling.
I took these out for a brief maxcpus=1 spin yesterday, and noticed
something. Running 4 copies of chew-max, one as a user, the context
switch rate was high (~1800/s). I increased sched_min_granularity_ns to
see if that would lower it, and it did, but it also upset fairness.
With sched_min_granularity_ns bumped to half of sched_latency_ns (40ms
default) it was a largish skew.
top - 06:58:46 up 3 min, 15 users, load average: 4.71, 2.53, 1.04
Tasks: 214 total, 9 running, 204 sleeping, 0 stopped, 1 zombie
Cpu(s): 39.0%us, 61.0%sy, 0.0%ni, 0.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ P COMMAND
5389 mikeg 20 0 1464 364 304 R 40.1 0.0 0:29.71 0 chew-max
5373 root 20 0 1464 364 304 R 19.0 0.0 0:16.30 0 chew-max
5388 root 20 0 1464 364 304 R 19.0 0.0 0:15.79 0 chew-max
5374 root 20 0 1464 364 304 R 18.6 0.0 0:15.90 0 chew-max
-Mike
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