[libvirt] [PATCH 2/3] qemu: Keep the affinity when creating cgroup for emulator thread

[Osier Yang]

On 2012年10月24日 21:17, Martin Kletzander wrote:
> On 10/24/2012 12:00 PM, Osier Yang wrote:
>> When the cpu placement model is "auto", it sets the affinity for
>> domain process with the advisory nodeset from numad, however,
>> creating cgroup for the domain process (called emulator thread
>> in some contexts) later overrides that with pinning it to all
>> available pCPUs.
>>
>> How to reproduce:
>>
>>    * Configure the domain with "auto" placement for<vcpu>, e.g.
>>      <vcpu placement='auto'>4</vcpu>
>>    * % virsh start dom
>>    * % cat /proc/$dompid/status
>>
>> Though the emulator cgroup cause conflicts, but we can't simply
>> prohibit creating it, as other tunables are still useful, such
>> as "emulator_period", which is used by API
>> virDomainSetSchedulerParameter. So this patch doesn't prohibit
>> creating the emulator cgroup, but inherit the nodeset from numad,
>> and reset the affinity for domain process.
>>
>> * src/qemu/qemu_cgroup.h: Modify definition of qemuSetupCgroupForEmulator
>>                            to accept the passed nodenet
>> * src/qemu/qemu_cgroup.c: Set the affinity with the passed nodeset
>> ---
>>   src/qemu/qemu_cgroup.c  |   17 ++++++++++++++---
>>   src/qemu/qemu_cgroup.h  |    3 ++-
>>   src/qemu/qemu_process.c |    2 +-
>>   3 files changed, 17 insertions(+), 5 deletions(-)
>>
>> diff --git a/src/qemu/qemu_cgroup.c b/src/qemu/qemu_cgroup.c
>> index db371a0..8e99c01 100644
>> @@ -698,6 +706,9 @@ int qemuSetupCgroupForEmulator(struct qemud_driver *driver,
>>               if (rc<  0)
>>                   goto cleanup;
>
> In case you go to the cleanup here, cpumask is not free()'d.

Ah, okay.

I will squash the following in:

diff --git a/src/qemu/qemu_cgroup.c b/src/qemu/qemu_cgroup.c
index 1754d6f..8f8ef08 100644
--- a/src/qemu/qemu_cgroup.c
+++ b/src/qemu/qemu_cgroup.c
@@ -706,9 +706,6 @@ int qemuSetupCgroupForEmulator(struct qemud_driver 
*driver,
              if (rc < 0)
                  goto cleanup;
          }
-
-        if (def->placement_mode == VIR_DOMAIN_CPU_PLACEMENT_MODE_AUTO)
-            virBitmapFree(cpumask);
          cpumask = NULL; /* sanity */
      }

@@ -725,6 +722,8 @@ int qemuSetupCgroupForEmulator(struct qemud_driver 
*driver,
      return 0;

  cleanup:
+    virBitmapFree(cpumap);
+
      if (cgroup_emulator) {
          virCgroupRemove(cgroup_emulator);
          virCgroupFree(&cgroup_emulator);