[Libvir] [PATCH] an irregular value is set as 'CPU Affinity' by virsh vcpupin
Daniel P. Berrange
berrange at redhat.com
Wed Jan 9 21:09:00 UTC 2008
On Wed, Jan 09, 2008 at 04:02:05AM +0000, Daniel P. Berrange wrote:
> On Tue, Jan 08, 2008 at 06:42:40PM +0900, Saori Fukuta wrote:
> > Hi,
> >
> > There is a difference between 'CPU Affinity' of 'virsh vcpuinfo' and
> > 'CPU Affinity' of 'xm vcpu-list' when I set the vcpu affinity by
> > 'virsh vcpupin'. i.e. 'xm vcpu-list' shows wrong value.
> > But there is no difference between them when I set by 'xm vcpu-pin'.
> >
> > (a) set by 'virsh vcpupin'
> > # virsh vcpupin guest_dom 0 1
> > # virsh vcpuinfo guest_dom
> > VCPU: 0
> > CPU: 1
> > State: blocked
> > CPU time: 17.1s
> > CPU Affinity: -y------
> >
> > # xm vcpu-list guest_dom
> > Name ID VCPUs CPU State Time(s) CPU Affinity
> > guest_dom 13 0 1 -b- 17.1 any cpu
> >
> > (b) set by 'xm vcpu-pin'
> > # xm vcpu-pin guest_dom 0 0
> > # virsh vcpuinfo guest_dom
> > VCPU: 0
> > CPU: 0
> > State: blocked
> > CPU time: 17.1s
> > CPU Affinity: y-------
> >
> > # xm vcpu-list guest_dom
> > Name ID VCPUs CPU State Time(s) CPU Affinity
> > guest_dom 13 0 0 -b- 17.1 0
> >
> > I guess that the allocated memory to cpumap must be 8-byte for Xen
> > because "xc_vcpu_setaffinity at libxc/xc_domain.c" is using uint64_t
> > as cpumap. But the libvirt is allocating only maplen size for cpumap.
> > virsh +--- cpumaplen ---+
> > (more than 1-byte)
> > xen +----------------- 8-byte -----------------+
> > (uint64_t)
> >
> > Then, an irregular value is set to the buffer that is more than the
> > number of physical CPU, because libvirt initialize maplen size only
> > (i.e. not initialize 8-byte buffer).
>
> Ok I understand what's going on now - Xen expects the CPU map to be
> exactly 8 bytes long, but libvirt only requires that it be large
> enough to hold the desired mapping. So the map passed in by the
> libvirt caller may be too small so the HV ends up reading garbage.
> This patch looks good to me.
I've tested and confirmed this is working as described, so have committed
the patch.
Dan.
--
|=- Red Hat, Engineering, Emerging Technologies, Boston. +1 978 392 2496 -=|
|=- Perl modules: http://search.cpan.org/~danberr/ -=|
|=- Projects: http://freshmeat.net/~danielpb/ -=|
|=- GnuPG: 7D3B9505 F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 -=|
More information about the libvir-list
mailing list