Messages in this thread | | | Date | Fri, 25 Oct 2002 13:38:57 +0100 | From | Dave Jones <> | Subject | Re: How to get number of physical CPU in linux from user space? |
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On Thu, Oct 24, 2002 at 04:02:29PM -0700, chrisl@vmware.com wrote: > It seems that /proc/cpuinfo will return the number of logical CPU. > If the machine has Intel Hyper-Thread enabled, that number is bigger > than physical CPU number. Usually twice as big. > > My question is, what is the reliable way for user space program > to detect the number of physical CPU in the current machine? > > If in it is in the kernel, I can read from cpu_sibling_map[] > or phys_cpu_id[]. But it seems not easy read that from > user space. > > Of course I can do "gdb /proc/kcore" to get them. But is there > any better way?
You can perform cpuid instructions in userspace to get the number of siblings per physical package.
-- | Dave Jones. http://www.codemonkey.org.uk - 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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