On Mon, Aug 06, 2012 at 05:09:04PM -0600, Eric Blake wrote:
> On 08/03/2012 12:36 AM, Hu Tao wrote:
> > From: Tang Chen <tangchen@xxxxxxxxxxxxxx>
> >
> > Hypervisor threads should also be pinned by sched_setaffinity(), just
> > the same as vcpu threads.
>
> Indeed, this fallback makes sense when cpuset cgroup is not present.
>
> Same question as earlier in the series - is affinity necessary when
> cpuset is in effect, or does cpuset already guarantee everything that
> affinity would already provide?
>
>
> > +static int
> > +qemuProcessSetHypervisorAffinites(virConnectPtr conn,
> > + virDomainObjPtr vm)
> > +{
> > + virDomainDefPtr def = vm->def;
> > + pid_t pid = vm->pid;
> > + unsigned char *cpumask = NULL;
> > + unsigned char *cpumap = NULL;
> > + virNodeInfo nodeinfo;
> > + int cpumaplen, hostcpus, maxcpu, i;
> > + int ret = -1;
> > +
> > + if (virNodeGetInfo(conn, &nodeinfo) != 0)
> > + return -1;
> > +
> > + if (!def->cputune.hypervisorpin)
> > + return 0;
> > +
> > + hostcpus = VIR_NODEINFO_MAXCPUS(nodeinfo);
> > + cpumaplen = VIR_CPU_MAPLEN(hostcpus);
> > + maxcpu = cpumaplen * 8;
>
> That's a magic number; I prefer CHAR_BIT from <limits.h>.
>
> Not your fault, but I really hate the amount of gross code duplication
> we have for dealing with conversions between strings, cpu maps, and
> bitmaps. It would be really nice to scrub the code to make nice helper
> functions that can provide easier conversion interfaces rather than open
> coding the conversion at each client.
>
> > +
> > + if (virProcessInfoSetAffinity(pid,
> > + cpumap,
> > + cpumaplen,
> > + maxcpu) < 0) {
>
> Does this work, or does it slam the affinity of all the vcpu children
> threads at the same time, even when we have used <vcpupin> to request
> different pinning?
Doesn't matter, existing children threads are not affected.
--
Thanks,
Hu Tao
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