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

[Osier Yang]

于 2011年05月07日 05:04, Bill Gray 写道:
>
> Looks like there is only a single call-back function --
> qemudSecurityHook() -- which has had some cgroup and CPU affinity code
> already added in it.
>
> Perhaps a good approach would be to add an invocation of a new function
> -- qemudInitMemAffinity() -- as a peer to the already present invocation
> of qemudInitCpuAffinity(). The qemudInitMemAffinity() function could use
> set_mempolicy() to bind or prefer local/specific memory (depending on
> whether the user specifies the explicit memory node list as mandatory or
> just advisory). Advisory / preferred won't work correctly for large,
> multi-node guests until multiple nodes can be preferred (presumably
> selected by amount of free memory resources when multiple nodes are
> preferred). It would also be helpful to have an additional attribute to
> specify interleaved memory.
>
> How does this approach sound?

Yes, the process should be like so, except the codes you are viewing
are not upstream libvirt. :)

Will add support for "interleave" in next patch series.

Regards
Osier
>
>
> On 05/06/2011 09:24 AM, Daniel P. Berrange wrote:
>> 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