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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] RE: [Xen-devel] Does dom0 see all physical processors? (RE:[Xen-ia64-devel] SAL INFO virtualization)
Hi, On Wed, 2006-04-05 at 07:07 -0700, Magenheimer, Dan (HP Labs Fort Collins) wrote: > I believe ppc has "paravirtualized spinlocks" in their Linux > kernel ppc64 does. From include/asm-ppc64/spinlock.h: /* * On a system with shared processors (that is, where a physical * processor is multiplexed between several virtual processors), * there is no point spinning on a lock if the holder of the lock * isn't currently scheduled on a physical processor. Instead * we detect this situation and ask the hypervisor to give the * rest of our timeslice to the lock holder. * * So that we can tell which virtual processor is holding a lock, * we put 0x80000000 | smp_processor_id() in the lock when it is * held. Conveniently, we have a word in the paca that holds this * value. */ A quick hack for this which simply did a yield sched_op when it detected a collision could be done in the same way from a paravirtualised kernel without any HV changes; but I think it would take extra scheduler help to do a directed yield to a specific CPU. --Stephen _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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