Author pitrou
Recipients beazley, dabeaz, flox, kristjan.jonsson, loewis, pitrou, torsten
Date 2010-04-06.22:35:15
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Message-id <1270593434.3518.62.camel@localhost>
In-reply-to <1270592538.55.0.790564762224.issue8299@psf.upfronthosting.co.za>
Content
[...]
> _PyObject_Call	403	99,02
[...]
> affinity off:
> Functions Causing Most Work
> Name	Samples	%
[...]
> _PyObject_Call	1.936	99,23
[...]
> _threadstartex	1.934	99,13
> 
> When we run on both cores, we get four times as many L1 instruction cache hits!

You mean we get 4x the number of cache /misses/, right?

This analysis is gratuitous if you can't evaluate/measure/calculate the
actual cost (in proportion of total elapsed or CPU time) of the
instruction cache misses. Perhaps it is actually negligible and the
slowdown is caused by something else.

> How best to combat this?  I'll do some experiments on Windows.
> Perhaps we can identify cpu-bound threads and group them on a single
> core.

IMHO, the OS should handle this. I don't think ad-hoc platform-specific
CPU affinity tweaks belong in the Python core.
History
Date User Action Args
2010-04-06 22:35:17pitrousetrecipients: + pitrou, loewis, beazley, kristjan.jonsson, flox, dabeaz, torsten
2010-04-06 22:35:15pitroulinkissue8299 messages
2010-04-06 22:35:15pitroucreate