Re: [libvirt] [Xen-devel] libvirt/libxl implemetation of get_online_cpu / virNodeGetCPUMap?
On Tue, 2015-02-24 at 13:10 +0000, Ian Campbell wrote:
On Tue, 2015-02-24 at 12:41 +0000, Anthony PERARD wrote:
> What libxl API those provide this information, if it exist?
>
> I found libxl_get_online_cpus() but that not enough. They want a
> bitmap.
I think that is all which currently exists, at least at the libxl level,
you may need to add a new interface.
It'd be worth looking into the various host numa interfaces -- perhaps
one of them indirectly exposes what you want?
Given Daniel's latest emails, I'm not sure this is useful but
libxl_get_cpu_topology() should put LIBXL_CPUTOPOLOGY_INVALID_ENTRY in
all the fields of the i-eth element of the array it returns, if the
i-eth pcpu is offline (see the implementation of XEN_SYSCTL_topologyinfo
in xen/common/sysctl.c).
So, scanning that array and constructing the bitmap according to whether
or not we find that marker on the various elements would be the way to
go, I would say.
I've actually never tested this, i.e., I've never tried offlining a pcpu
on the host. I'll give it a go as soon as I find 5 minutes, and let know
if it works.
Regards,
Dario
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