Messages in this thread | | | Subject | Re: Linux 2.4.17-pre5 | From | (Eric W. Biederman) | Date | 11 Dec 2001 02:00:23 -0700 |
| |
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/
| |