Re: Possible bug from kernel 2.6.22 and above, 2.6.24-rc4

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From: Ingo Molnar
Date: Wednesday, December 5, 2007 - 8:40 am

* Jie Chen <chen@jlab.org> wrote:


ok, i had a look at your data, and i think this is the result of the 
scheduler balancing out to idle CPUs more agressively than before. Doing 
that is almost always a good idea though - but indeed it can result in 
"bad" numbers if all you do is to measure the ping-pong "performance" 
between two threads. (with no real work done by any of them).

the moment you saturate the system a bit more, the numbers should 
improve even with such a ping-pong test.

do you have testcode (or a modification of your testcase sourcecode) 
that simulates a real-life situation where 2.6.24-rc4 performs not as 
well as you'd like it to see? (or if qmt.tar.gz already contains that 
then please point me towards that portion of the test and how i should 
run it - thanks!)

	Ingo
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Messages in current thread:
Re: Possible bug from kernel 2.6.22 and above, Eric Dumazet, (Wed Nov 21, 3:14 pm)
Re: Possible bug from kernel 2.6.22 and above, Jie Chen, (Wed Nov 21, 6:52 pm)
Re: Possible bug from kernel 2.6.22 and above, Simon Holm , (Wed Nov 21, 7:32 pm)
Re: Possible bug from kernel 2.6.22 and above, Jie Chen, (Wed Nov 21, 7:58 pm)
Re: Possible bug from kernel 2.6.22 and above, 2.6.24-rc4, Ingo Molnar, (Wed Dec 5, 8:40 am)
Re: Possible bug from kernel 2.6.22 and above, Peter Zijlstra, (Wed Dec 5, 1:36 pm)
Re: Possible bug from kernel 2.6.22 and above, Jie Chen, (Wed Dec 5, 1:53 pm)
Re: Possible bug from kernel 2.6.22 and above, 2.6.24-rc4, Peter Zijlstra, (Wed Dec 12, 5:49 am)