Messages in this thread | | | Date | Fri, 23 Jul 2004 14:00:14 +0200 | From | Ingo Molnar <> | Subject | Re: [patch] voluntary-preempt-2.6.8-rc2-I3 |
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* Paolo Ciarrocchi <paolo.ciarrocchi@gmail.com> wrote:
> Hi Ingo, > thanks for the clarification. > > What about performance of vanilla vs voluntary-preempt-2.6.8-rc2-I3 ? > Do you have numbers available ? Can we, somehow, support you ?
All known performance problems have been fixed in -I4. The focus is mainly on latency. You can best support this patch by trying it out and doing measurements - both latency and throughput measurements are welcome. Latency measurement can be done via the latencytest tool:
http://www.alsa-project.org/~iwai/latencytest-0.5.4.tar.gz
If you enable both CONFIG_PREEMPT_VOLUNTARY and CONFIG_PREEMPT then you can use the /proc/sys/kernel/voluntary_preemption|kernel_preemption sysctl knobs to turn the preemption features on/off. The following flag combinations can be used to do comparisons:
vanilla: vp:0 kp:0 CONFIG_PREEMPT: vp:0 kp:1 voluntary-preempt: vp:1 kp:0 voluntary-preempt + CONFIG_PREEMPT: vp:1 kp:1 voluntary-preempt + softirq defer: vp:2 kp:0 [default] voluntary-preempt + softirq defer + CONFIG_PREEMPT: vp:2 kp:1
each of the above combinations should work and should pretty exactly represent that particular kernel (i.e. you can get vanilla non-preemptible 2.6.8-rc2 kernel behavior by switching both flags on) - but i typically use the default one for testing.
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