Messages in this thread | | | Date | Tue, 18 Jul 2006 12:03:15 -0700 | From | "Keith Mannthey" <> | Subject | Re: CPU numbering & hyperthreading |
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On 7/17/06, Andrew Athan <aathan_linux_kernel_1542@cloakmail.com> wrote: > > On an Intel Xeon dual CPU machine running 2.6.16 and up... > > I have two highly CPU/memory/network intensive processes with 3-5 > threads each. I am using sched_setaffinity calls to make sure these two > processes never compete for the same physical CPU. Am I right to assume > that CPU #0 and #1 vs CPU #2 and #3 are separate physical CPUs on a > 2-CPU w/ hyperthreading box? > > I've spent some time looking, but I did not find documentation on > exactly how CPUs are numbered in a hyperthreaded box.
It is up to the bios how the cpus are layed out. Any easy way to check for the info you want is to look at /proc/cpuinfo (you can also get the info out of /sys/devices/system/cpu/cpu[x]/topology). Cpus with the same physical id are in the same package. The info (core_id core_siblings physical_package_id thread_siblings and like kind from proc) describes the topology.
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