Re: BFS vs. mainline scheduler benchmarks and measurements

From: Felix Fietkau
Date: Sat Sep 19 2009 - 16:34:12 EST


Ingo Molnar wrote:
> * Felix Fietkau <nbd@xxxxxxxxxxx> wrote:
>
>> Ingo Molnar wrote:
>> > * Felix Fietkau <nbd@xxxxxxxxxxx> wrote:
>> >> I did some tests with BFS v230 vs CFS on Linux 2.6.30 on a different
>> >> MIPS device (Atheros AR2317) with 180 MHz and 16 MB RAM. When running
>> >> iperf tests, I consistently get the following results when running the
>> >> transfer from the device to my laptop:
>> >>
>> >> CFS: [ 5] 0.0-60.0 sec 107 MBytes 15.0 Mbits/sec
>> >> BFS: [ 5] 0.0-60.0 sec 119 MBytes 16.6 Mbits/sec
>> >>
>> >> The transfer speed from my laptop to the device are the same with BFS
>> >> and CFS. I repeated the tests a few times just to be sure, and I will
>> >> check vmstat later.
>> >
>> > Which exact mainline kernel have you tried? For anything performance
>> > related running latest upstream -git (currently at 202c467) would be
>> > recommended.
>>
>> I used the OpenWrt-patched 2.6.30. Support for the hardware that I
>> tested with hasn't been merged upstream yet. Do you think that the
>> scheduler related changes after 2.6.30 are relevant for non-SMP
>> performance as well? If so, I'll work on a test with latest upstream
>> -git with the necessary patches when I have time for it.
>
> Dont know - it's hard to tell what happens without basic analysis tools.
> Is there _any_ way to profile what happens on that system? (Do hrtimers
> work on it that could be used to profile it?)
oprofile doesn't have any support for it (mips r4k, no generic
perfcounters), the only usable clock source is a simple cpu cycle
counter (which is also used for the timer interrupt).

- Felix
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