On Wed, May 21, 2008 at 10:59:28AM -0400, Daniel Veillard wrote:
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).
Well I believe the Solaris folks disable QEMU driver entirely, but its easy enough to add a configure.ac check for sched_setaffinity/sched_getaffinity and disable them. You can also pin regular QEMU - though its limited to a single vCPU.
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 ?
Sorry, was slightly misleading. We detect the mapping at startup and cache it, but don't print any errors at that point if it is not supported. Only when someone runs virDomainPinVcpu()/virDomainGetVcpus() will they get an error message. Dan. -- |: Red Hat, Engineering, Boston -o- http://people.redhat.com/berrange/ :| |: http://libvirt.org -o- http://virt-manager.org -o- http://ovirt.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: GnuPG: 7D3B9505 -o- F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 :|