Messages in this thread | | | From | (Eric W. Biederman) | Subject | Re: 2.6.19-rc1: x86_64 slowdown in lmbench's fork | Date | Fri, 03 Nov 2006 10:35:36 -0700 |
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Tim Chen <tim.c.chen@linux.intel.com> writes:
> On Fri, 2006-11-03 at 03:11 +0100, Adrian Bunk wrote: > >> >> What's your CONFIG_NR_CPUS setting that you are seeing such a big >> regression? >> > > CONFIG_NR_CPUS is set to 8.
Ugh. This simply changes NR_IRQS from 256 to 512. Changing the size of data from 1K to 2K.
So unless there is some other array that is sized by NR_IRQs in the context switch path which could account for this in other ways. It looks like you just got unlucky.
The only hypothesis that I can seem to come up with is that maybe you are getting an extra tlb now that you didn't use to. I think the per cpu area is covered by huge pages but maybe not.
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