Re: O(1) scheduler gives big boost to tbench 192

[Jussi Laako <jussi.laako@kolumbus.fi>]

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Mike Kravetz wrote:
> 
> Is there anything simple I can do to check the latencies of the
> pthread_cond_*() functions?  I'd like to do some analysis of
> scheduler behavior, but am unfamiliar with the user level code.

I just wrote small test program (attached) for testing this. It is similar
to my app, but for this test the soundcard is just used more as a timing
source.

Adjust the buffer size so that it's on the edge of missing blocks then
generate some system load to run it over the edge to see how sensitive it is
and how many blocks are lost. I can see clear difference using kernel with
original scheduler and with kernel having the O(1) scheduler.

It's quite sensitive when you run it without setuid privileges, but normal
situation is to run it at SCHED_FIFO.

Because of famous ReiserFS tailmerging feature lost-and-rewrote part of it
after crashing system with it. Found the the binary overwriting top of it
after reboot... I was happy to have copied it to another machine over NFS
just a few minutes before crash, so not much was lost.


	- Jussi Laako

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