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On Thu, Dec 08, 2005 at 07:12:12AM +0100, Andi Kleen wrote: > On Wed, Dec 07, 2005 at 09:38:25PM -0800, David S. Miller wrote: > > From: Dave Jones <davej@redhat.com> > > Date: Thu, 8 Dec 2005 00:33:02 -0500 > > > > > On Thu, Dec 08, 2005 at 06:26:32AM +0100, Andi Kleen wrote: > > > > > > > The possible map is fixed kind of BTW in 2.6.15rc*. It was a side effect > > > > of CPU hotplug, which now uses a better algorithm to guess the > > > > number of possible CPUs. In 2.6.15 you will just get half the number > > > > of available CPUs in addition by default > > > > > > Yep, I noticed it offers a maximum of 6 cpus on my way. > > > As a sidenote, seems kinda funny (and wasteful maybe?), doing this > > > on a lot of hardware that isn't hotplug capable. (Whilst I could > > > disable cpu hotplug in my local build, this isn't an answer for > > > a generic distro kernel). > > If you can figure out a way to detect this please share. > The ACPI designers unfortunately didn't think that far > (they did it right for memory hotplug, but not for CPU) > > I invented an ACPI extensin for it, but it's non standard > so the half of CPUs is used as a default unless overwritten > (additional_cpus=NUM) > > Anyways I changed it earlier to 1 additional CPU by default. Just guessing seems to be pretty guaranteed to give the wrong answer. I think it makes more sense to say "if your BIOS doesn't give the relevant info (as is usually the case), boot with additional_cpus) Penalising the many for the needs of the few just seems wrong. Dave - 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/ | ||||||||||||
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