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 ?
In any case looks fine, +1
Daniel
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