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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. > > This can be dangerous btw, as some subsystem such as netfilter > allocate enormous datastructures based upon the largest possible > cpu number in the system. It is a big improvement in fact. Previously with NR_CPUS==128 (default on some distros) and CPU_HOTPLUG enabled it would always allocate several hundred KB of just standard per cpu data unnecessarily. -Andi - 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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