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qemu: Don't cache NUMA caps

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In v6.0.0-rc1~439 (and friends) we tried to cache NUMA
capabilities because we assumed they are immutable. And to some
extent they are (NUMA hotplug is not a thing, is it). However,
our capabilities contain also some runtime info that can change,
e.g. hugepages pool allocation sizes or total amount of memory
per node (host side memory hotplug might change the value).

Because of the caching we might not be reporting the correct
runtime info in 'virsh capabilities'.

The NUMA caps are used in three places:

  1) 'virsh capabilities'
  2) domain startup, when parsing numad reply
  3) parsing domain private data XML

In cases 2) and 3) we need NUMA caps to construct list of
physical CPUs that belong to NUMA nodes from numad reply. And
while this may seem static, it's not really because of possible
CPU hotplug on physical host.

There are two possible approaches:

  1) build a validation mechanism that would invalidate the
     cached NUMA caps, or
  2) drop the caching and construct NUMA caps from scratch on
     each use.

In this commit, the latter approach is implemented, because it's
easier.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1819058
Fixes: 1a1d848694
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>
This commit is contained in:
Michal Privoznik 2020-12-02 09:26:30 +01:00
parent f5e8715a8b
commit 40a162f83e
5 changed files with 7 additions and 37 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

23
src/qemu/qemu_conf.c
View File

@ -1288,27 +1288,6 @@ virQEMUDriverCreateXMLConf(virQEMUDriverPtr driver,
}
virCapsHostNUMAPtr
virQEMUDriverGetHostNUMACaps(virQEMUDriverPtr driver)
{
virCapsHostNUMAPtr hostnuma;
qemuDriverLock(driver);
if (!driver->hostnuma)
driver->hostnuma = virCapabilitiesHostNUMANewHost();
hostnuma = driver->hostnuma;
qemuDriverUnlock(driver);
if (hostnuma)
virCapabilitiesHostNUMARef(hostnuma);
return hostnuma;
}
virCPUDefPtr
virQEMUDriverGetHostCPU(virQEMUDriverPtr driver)
{
@ -1380,7 +1359,7 @@ virCapsPtr virQEMUDriverCreateCapabilities(virQEMUDriverPtr driver)
"DOI \"%s\"", model, doi);
}
caps->host.numa = virQEMUDriverGetHostNUMACaps(driver);
caps->host.numa = virCapabilitiesHostNUMANewHost();
caps->host.cpu = virQEMUDriverGetHostCPU(driver);
return g_steal_pointer(&caps);
}

6
src/qemu/qemu_conf.h
View File

@ -270,11 +270,6 @@ struct _virQEMUDriver {
*/
virCapsPtr caps;
/* Lazy initialized on first use, immutable thereafter.
* Require lock to get the pointer & do optional initialization
*/
virCapsHostNUMAPtr hostnuma;
/* Lazy initialized on first use, immutable thereafter.
* Require lock to get the pointer & do optional initialization
*/
@ -337,7 +332,6 @@ virQEMUDriverConfigSetDefaults(virQEMUDriverConfigPtr cfg);
virQEMUDriverConfigPtr virQEMUDriverGetConfig(virQEMUDriverPtr driver);
virCapsHostNUMAPtr virQEMUDriverGetHostNUMACaps(virQEMUDriverPtr driver);
virCPUDefPtr virQEMUDriverGetHostCPU(virQEMUDriverPtr driver);
virCapsPtr virQEMUDriverCreateCapabilities(virQEMUDriverPtr driver);
virCapsPtr virQEMUDriverGetCapabilities(virQEMUDriverPtr driver,

7
src/qemu/qemu_domain.c
View File

@ -2498,8 +2498,7 @@ qemuDomainObjPrivateXMLParseVcpu(xmlNodePtr node,
static int
qemuDomainObjPrivateXMLParseAutomaticPlacement(xmlXPathContextPtr ctxt,
qemuDomainObjPrivatePtr priv,
virQEMUDriverPtr driver)
qemuDomainObjPrivatePtr priv)
{
g_autoptr(virCapsHostNUMA) caps = NULL;
g_autofree char *nodeset = NULL;
@ -2513,7 +2512,7 @@ qemuDomainObjPrivateXMLParseAutomaticPlacement(xmlXPathContextPtr ctxt,
if (!nodeset && !cpuset)
return 0;
if (!(caps = virQEMUDriverGetHostNUMACaps(driver)))
if (!(caps = virCapabilitiesHostNUMANewHost()))
return -1;
/* Figure out how big the nodeset bitmap needs to be.
@ -3114,7 +3113,7 @@ qemuDomainObjPrivateXMLParse(xmlXPathContextPtr ctxt,
}
VIR_FREE(nodes);
if (qemuDomainObjPrivateXMLParseAutomaticPlacement(ctxt, priv, driver) < 0)
if (qemuDomainObjPrivateXMLParseAutomaticPlacement(ctxt, priv) < 0)
goto error;
if ((tmp = virXPathString("string(./libDir/@path)", ctxt)))

1
src/qemu/qemu_driver.c
View File

@ -1136,7 +1136,6 @@ qemuStateCleanup(void)
virObjectUnref(qemu_driver->qemuCapsCache);
virObjectUnref(qemu_driver->xmlopt);
virCPUDefFree(qemu_driver->hostcpu);
virCapabilitiesHostNUMAUnref(qemu_driver->hostnuma);
virObjectUnref(qemu_driver->caps);
ebtablesContextFree(qemu_driver->ebtables);
VIR_FREE(qemu_driver->qemuImgBinary);

7
src/qemu/qemu_process.c
View File

@ -6197,8 +6197,7 @@ qemuProcessUpdateGuestCPU(virDomainDefPtr def,
static int
qemuProcessPrepareDomainNUMAPlacement(virQEMUDriverPtr driver,
virDomainObjPtr vm)
qemuProcessPrepareDomainNUMAPlacement(virDomainObjPtr vm)
{
qemuDomainObjPrivatePtr priv = vm->privateData;
g_autofree char *nodeset = NULL;
@ -6226,7 +6225,7 @@ qemuProcessPrepareDomainNUMAPlacement(virQEMUDriverPtr driver,
if (virBitmapParse(nodeset, &numadNodeset, VIR_DOMAIN_CPUMASK_LEN) < 0)
return -1;
if (!(caps = virQEMUDriverGetHostNUMACaps(driver)))
if (!(caps = virCapabilitiesHostNUMANewHost()))
return -1;
/* numad may return a nodeset that only contains cpus but cgroups don't play
@ -6428,7 +6427,7 @@ qemuProcessPrepareDomain(virQEMUDriverPtr driver,
}
virDomainAuditSecurityLabel(vm, true);
if (qemuProcessPrepareDomainNUMAPlacement(driver, vm) < 0)
if (qemuProcessPrepareDomainNUMAPlacement(vm) < 0)
return -1;
}