[libvirt] [PATCH 4/5] qemu: Build command line for NUMA tuning

[Daniel P. Berrange]

On Fri, May 06, 2011 at 09:20:18PM +0800, Osier Yang wrote:
> 于 2011年05月06日 17:23, Daniel P. Berrange 写道:
> >On Thu, May 05, 2011 at 04:30:30PM -0400, Bill Gray wrote:
> >>
> >>Hi Daniel,
> >>
> >>How can we get NUMA-aligned memory and CPUs if we apply binding APIs
> >>after the process has already started?   Might not all the memory
> >>already be allocated on the wrong nodes by then?
> >
> >The policy has to be set after fork'ing the new QEMU process, but
> >before exec'ing QEMU. This is essentially what you're doing with
> >numactl, but with the problem of an extra binary that screws up
> >the SELinux domain transitions from libvirtd_t ->  svirt_t.
> >
> >>For expert users, what are the problems with starting qemu with an
> >>external numactl command (with --cpunodebind and --membind) to
> >>guarantee optimal alignment?
> >
> >Adding an intermediate process will prevent the neccessary SELinux
> >domain transitions from working. We don't want to allow the
> >numactl binary to be able to transition to svirt_t because that
> >would be inappropriate for most users of numactl
> 
> This make sense, as you said in another mail, perhaps we need to do some
> work on __virExec, will make v2 series. Thanks for feedback.

Not virExec, but rather in the QEMU exec hook function


Daniel
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