[libvirt] [PATCH 1/3] qemu, lxc: Change host CPU detection logic.
Eric Blake
eblake at redhat.com
Wed Oct 31 00:29:55 UTC 2012
On 10/26/2012 07:19 AM, Viktor Mihajlovski wrote:
> The drivers for QEMU and LXC use virNodeGetInfo to determine the
> number of host CPUs. This approach can lead to a wrong (too small)
> number if one or more CPUs are offline.
> It is better to use virNodeGetCPUMap if available, which is the
> case here.
Hmm - ever since commit 4fbf322 added the simpler nodeGetCPUCount, that
function seems like a better option than calling virNodeGetCPUMap with
NULL arguments if all we need is the number of available (and possibly
offline) CPUs.
>
> Signed-off-by: Viktor Mihajlovski <mihajlov at linux.vnet.ibm.com>
> ---
> src/lxc/lxc_controller.c | 8 +++-----
> src/qemu/qemu_driver.c | 12 +++---------
> src/qemu/qemu_process.c | 10 ++++------
> 3 files changed, 10 insertions(+), 20 deletions(-)
>
> diff --git a/src/lxc/lxc_controller.c b/src/lxc/lxc_controller.c
> index a41c903..e9720bc 100644
> --- a/src/lxc/lxc_controller.c
> +++ b/src/lxc/lxc_controller.c
> @@ -492,17 +492,15 @@ static int virLXCControllerSetupNUMAPolicy(virLXCControllerPtr ctrl)
> static int virLXCControllerSetupCpuAffinity(virLXCControllerPtr ctrl)
> {
> int hostcpus, maxcpu = CPU_SETSIZE;
> - virNodeInfo nodeinfo;
> virBitmapPtr cpumap, cpumapToSet;
>
> VIR_DEBUG("Setting CPU affinity");
>
> - if (nodeGetInfo(NULL, &nodeinfo) < 0)
> - return -1;
> -
> /* setaffinity fails if you set bits for CPUs which
> * aren't present, so we have to limit ourselves */
> - hostcpus = VIR_NODEINFO_MAXCPUS(nodeinfo);
> + if ((hostcpus = nodeGetCPUMap(NULL, NULL, NULL, 0)) < 0)
> + return -1;
> +
> if (maxcpu > hostcpus)
> maxcpu = hostcpus;
But the idea of using the simplest function possible instead of calling
nodeGetInfo() and discarding the bulk of the struct makes sense.
Looking forward to v2.
> @@ -1923,7 +1921,7 @@ qemuPrepareCpumap(struct qemud_driver *driver,
> bool result;
> if (virBitmapGetBit(nodemask, i, &result) < 0) {
> virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
> - _("Failed to covert nodeset to cpuset"));
> + _("Failed to convert nodeset to cpuset"));
> virBitmapFree(cpumap);
I noticed this one independently, and fixed it in commit dd0a704 before
even seeing this thread from you.
--
Eric Blake eblake at redhat.com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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