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virnuma: Allow multiple nodes for preferred policy 

In the past, the preferred policy
(VIR_DOMAIN_NUMATUNE_MEM_PREFERRED) required exactly one (host)
NUMA node. This made sense because:

  1) the libnuma API - numa_set_preferred() allowed exactly one
     node, because
  2) corresponding kernel syscall (__NR_set_mempolicy) accepted
     exactly one node (for MPOL_PREFERRED mode).

But things have changed since then. Firstly, kernel introduced
new MPOL_PREFERRED_MANY mode (v5.15-rc1~107^2~21) which was then
exposed in libnuma as numa_set_preferred_many() (v2.0.15~24).

Fortunately, libnuma also exposes numa_has_preferred_many() which
returns whether the kernel has support for the new mode (1) or
not (0).

Putting this all together, we can lift our check for sufficiently
new kernel and libnuma.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=2151064
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
This commit is contained in:
Michal Privoznik 2022-12-09 14:41:24 +01:00
parent 7166d26fc9
commit 53369ad062
2 changed files with 26 additions and 2 deletions
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3
meson.build
View File

@ -1059,6 +1059,9 @@ endif
numactl_dep = cc.find_library('numa', required: get_option('numactl'))
if numactl_dep.found()
conf.set('WITH_NUMACTL', 1)
if cc.has_function('numa_set_preferred_many', dependencies: numactl_dep)
conf.set('WITH_NUMACTL_SET_PREFERRED_MANY', 1)
endif
endif
openwsman_version = '2.6.3'

25
src/util/virnuma.c
View File

@ -93,7 +93,6 @@ virNumaSetupMemoryPolicy(virDomainNumatuneMemMode mode,
virBitmap *nodeset)
{
nodemask_t mask;
int node = -1;
int bit = 0;
size_t i;
int maxnode = 0;
@ -128,7 +127,19 @@ virNumaSetupMemoryPolicy(virDomainNumatuneMemMode mode,
case VIR_DOMAIN_NUMATUNE_MEM_PREFERRED:
{
# ifdef WITH_NUMACTL_SET_PREFERRED_MANY
struct bitmask *bitmask = NULL;
# endif
int G_GNUC_UNUSED node = -1;
int nnodes = 0;
bool has_preferred_many = false;
# ifdef WITH_NUMACTL_SET_PREFERRED_MANY
if (numa_has_preferred_many() > 0) {
has_preferred_many = true;
}
# endif
for (i = 0; i < NUMA_NUM_NODES; i++) {
if (nodemask_isset(&mask, i)) {
node = i;
@ -136,15 +147,25 @@ virNumaSetupMemoryPolicy(virDomainNumatuneMemMode mode,
}
}
if (nnodes != 1) {
if (!has_preferred_many && nnodes != 1) {
virReportError(VIR_ERR_INTERNAL_ERROR,
"%s", _("NUMA memory tuning in 'preferred' mode "
"only supports single node"));
return -1;
}
/* The following automatically sets MPOL_PREFERRED_MANY
* whenever possible, so no need to special case it. */
numa_set_bind_policy(0);
# ifdef WITH_NUMACTL_SET_PREFERRED_MANY
bitmask = numa_bitmask_alloc(maxnode + 1);
copy_nodemask_to_bitmask(&mask, bitmask);
numa_set_preferred_many(bitmask);
numa_bitmask_free(bitmask);
# else
numa_set_preferred(node);
# endif
}
break;