Re: [libvirt] PATCH: Support vCPU pinning in QEMU driver

On Fri, May 16, 2008 at 10:47:40PM +0100, Daniel P. Berrange wrote: > KVM added ability to get the thread ID for vCPUs via the monitor > > (qemu) info cpus > * CPU #0: pc=0x00000000000ffff0 thread_id=11463 > CPU #1: pc=0x00000000fffffff0 thread_id=11464 > CPU #2: pc=0x00000000fffffff0 thread_id=11465 > > With this we have enough information to be able to support vCPU pinning in > the QEMU driver for KVM. For QEMU/KQEMU it is trivial, since they have a > single thread. > > The following patch implements CPU pinning and fetching of CPU affinity > information. In this example I pin one of the 2 cpus in a guest: [...] > This is implemented using sched_setaffinity/sched_getaffinity which are > Linux specific. There doesn't appear to be a portable process affinity > API in POSIX. looks fine to me. I guess the main use will be for KVM which is Linux specific, so that should not be a big deal IMHO (if we could just make sure the code doesn't bomb at compile time on say Solaris).

> If the KVM instance does not support the 'thread_id' data in 'info cpus', > we simply print out a suitable error message. We detect the mapping at > startup and cache it thereafter. Hum, okay, seems that should work just fine even if one migrates or save/restore. Is the error reported each time one starts a new VM ?