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 - 9:47 am

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


so right now the results dont seem to be too bad to me - the higher 
overhead comes from two threads running on two different cores and 
incurring the overhead of cross-core communications. In a true 
spread-out workloads that synchronize occasionally you'd get the same 
kind of overhead so in fact this behavior is more informative of the 
real overhead i guess. In 2.6.21 the two threads would stick on the same 
core and produce artificially low latency - which would only be true in 
a real spread-out workload if all tasks ran on the same core. (which is 
hardly the thing you want on openmp)

In any case, if i misinterpreted your numbers or if you just disagree, 
or if have a workload/test that shows worse performance that it 
could/should, let me know.

	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, 9:47 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)