[lkml]   [2003]   [Dec]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [PATCH][RFC] make cpu_sibling_map a cpumask_t
On Sunday 07 December 2003 8:25 pm, Nick Piggin wrote:
> Hi guys,
> This is rather a trivial change but is not for 2.6.0.
> The patch is actually on top of some of my HT stuff so one part is
> slightly different, but its purpose is to gather feedback.
> It turns the cpu_sibling_map array from an array of cpus to an array
> of cpumasks. This allows handling of more than 2 siblings, not that
> I know of any immediate need.

There will probably be a need, although I don't know how soon. Some of the
Intel folks have not been hinting that there will be more than two siblings
in a future CPU. No, they have not been hinting at all. ;^)

> I think it generalises cpu_sibling_map sufficiently that it can become
> generic code. This would allow architecture specific code to build the
> sibling map, and then Ingo's or my HT implementations to build their
> scheduling descriptions in generic code.
> I'm not aware of any reason why the kernel should not become generally
> SMT aware. It is sufficiently different to SMP that it is worth
> specialising it, although I am only aware of P4 and POWER5 implementations.
> Best regards
> Nick
> P.S.
> I have an alternative to Ingo's HT scheduler which basically does
> the same thing. It is showing a 20% elapsed time improvement with a
> make -j3 on a 2xP4 Xeon (4 logical CPUs).
> Before Ingo's is merged, I would like to discuss the pros and cons of
> both approaches with those interested. If Ingo's is accepted I should
> still be able to port my other SMP/NUMA improvements on top of it.

James Cleverdon
IBM xSeries Linux Solutions
{jamesclv(Unix, preferred), cleverdj(Notes)} at us dot ibm dot comm
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

 \ /
  Last update: 2005-03-22 13:59    [W:0.115 / U:0.836 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site