On Wed, Apr 22, 2009 at 05:59:04PM -0400, John Baldwin wrote: > On Wednesday 22 April 2009 5:40:37 pm John Baldwin wrote: > > Author: jhb > > Date: Wed Apr 22 21:40:37 2009 > > New Revision: 191405 > > URL: http://svn.freebsd.org/changeset/base/191405 > > > > Log: > > Adjust the way we number CPUs on x86 so that we attempt to "group" all > > logical CPUs in a package. We do this by numbering the non-boot CPUs > > by starting with the first CPU whose APIC ID is after the boot CPU and > > wrapping back around to APIC ID 0 if needed rather than always starting > > at APIC ID 0. While here, adjust the cpu_mp_announce() routine to list > > CPUs based on the mapping established by assign_cpu_ids() rather than > > making assumptions about the algorithm assign_cpu_ids() uses. > > An example is probably in order for this to make sense. Suppose you have a > system with two quad-core CPUs. Package 0 has CPUs numbered 0, 1, 2, and 3. > Package 1 has CPUs numbered 4, 5, 6, and 7. With the old code, if package 0 > won the election to be the boot processor, then CPU 0 would be the BSP and > the logical IDs would match the APIC IDs. However, if package 1 won the > election during POST, then CPU 0 would be APIC ID 4 on package 0 followed by > CPU 1 being APIC ID 0, CPU 2 being APIC ID 1, etc. Thus, when CPU 0 was the > boot CPU you had a nice grouping where CPUs 0-3 were a single package and > CPUs 4-7 were another package. However, when CPU 4 was the boot CPU, CPUs 0 > and 5-7 where one package, and CPUs 1-4 where the second package. The effect > of this patch is to change the case when CPU 4 is the boot CPU such that CPUs > 0-3 are now all from CPU 4's package (APIC IDs 4-7), and CPUs 4-7 are from > the other package (APIC IDs 0-3). What this means, in turn, is that in both > cases you now always have CPUs 0-3 as one package and CPUs 4-7 as another > package regardless of which CPU wins the boot-time election.
What if I have HT turned on? Do they bunch up with the "real" CPU IDs
or all together at the end?
Ceri
--
That must be wonderful! I don't understand it at all.
-- Moliere
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