lkml.org 
[lkml]   [2001]   [Dec]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: Linux 2.4.17-pre5
From
Date
Alan Cox <alan@lxorguk.ukuu.org.uk> writes:

> > If you number each CPU so its two IDs are smp_num_cpus()/2
> > apart, you will NOT need to put some crappy hack in the
> > scheduler to pack your CPUs correctly.
>
> Which is a major change to the x86 tree and an invasive one. Right now the
> X86 is doing a 1:1 mapping, and I can offer Marcelo no proof that somewhere
> buried in the x86 arch code there isnt something that assumes this or mixes
> a logical and physical cpu id wrongly in error.

Actually we don't do a 1:1 physical to logical mapping. I currently
have a board that has physical id's of: 0:6 and logical id's of 0:1
with no changes to the current x86 code.
>
> At best you are exploiting an obscure quirk of the current scheduler that is
> quite likely to break the moment someone factors power management into the
> idling equation (turning cpus off and on is more expensive so if you idle
> a cpu you want to keep it the idle one for PM). Congratulations on your
> zen like mastery of the scheduler algorithm. Now tell me it wont change in
> that property.

The idea of a cpu priority for filling sounds like a nice one. Even
if we don't use the cpu id bits for it.

Eric

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 13:18    [W:0.133 / U:0.420 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site