4:46 p.m.
From: Dario Faggioli <dario.faggioli(a)citrix.com>
Starting from Xen 4.2, libxl has all the bits and pieces in place
for retrieving an adequate amount of information about the host
NUMA topology. It is therefore possible, after a bit of shuffling,
to arrange those information in the way libvirt wants to present
them to the outside world.
Therefore, with this patch, the <topology> section of the host
capabilities is properly populated, when running on Xen, so that
we can figure out whether or not we're running on a NUMA host,
and what its characteristics are.
[raistlin@Zhaman ~]$ sudo virsh --connect xen:/// capabilities
<capabilities>
<host>
<cpu>
....
<topology>
<cells num='2'>
<cell id='0'>
<memory unit='KiB'>6291456</memory>
<cpus num='8'>
<cpu id='0' socket_id='1' core_id='0'
siblings='0-1'/>
<cpu id='1' socket_id='1' core_id='0'
siblings='0-1'/>
<cpu id='2' socket_id='1' core_id='1'
siblings='2-3'/>
<cpu id='3' socket_id='1' core_id='1'
siblings='2-3'/>
<cpu id='4' socket_id='1' core_id='9'
siblings='4-5'/>
<cpu id='5' socket_id='1' core_id='9'
siblings='4-5'/>
<cpu id='6' socket_id='1' core_id='10'
siblings='6-7'/>
<cpu id='7' socket_id='1' core_id='10'
siblings='6-7'/>
</cpus>
</cell>
<cell id='1'>
<memory unit='KiB'>6881280</memory>
<cpus num='8'>
<cpu id='8' socket_id='0' core_id='0'
siblings='8-9'/>
<cpu id='9' socket_id='0' core_id='0'
siblings='8-9'/>
<cpu id='10' socket_id='0' core_id='1'
siblings='10-11'/>
<cpu id='11' socket_id='0' core_id='1'
siblings='10-11'/>
<cpu id='12' socket_id='0' core_id='9'
siblings='12-13'/>
<cpu id='13' socket_id='0' core_id='9'
siblings='12-13'/>
<cpu id='14' socket_id='0' core_id='10'
siblings='14-15'/>
<cpu id='15' socket_id='0' core_id='10'
siblings='14-15'/>
</cpus>
</cell>
</cells>
</topology>
</host>
....
---
This would be a nice addtion to libvirt 1.1.2, wrapping up Dario's initial
work on NUMA support in the libxl driver. Since he is on vacation the next
weeks, I rebased his patch on the recent libxl capabilities cleanup.
src/libxl/libxl_conf.c | 116 +++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 116 insertions(+)
diff --git a/src/libxl/libxl_conf.c b/src/libxl/libxl_conf.c
index 73e2d49..6b0e89e 100644
--- a/src/libxl/libxl_conf.c
+++ b/src/libxl/libxl_conf.c
@@ -101,6 +101,119 @@ libxlCapsInitHost(libxl_ctx *ctx, virCapsPtr caps)
}
static int
+libxlCapsInitNuma(libxl_ctx *ctx, virCapsPtr caps)
+{
+ libxl_numainfo *numa_info = NULL;
+ libxl_cputopology *cpu_topo = NULL;
+ int nr_nodes = 0, nr_cpus = 0;
+ virCapsHostNUMACellCPUPtr *cpus = NULL;
+ int *nr_cpus_node = NULL;
+ size_t i;
+ int ret = -1;
+
+ /* Let's try to fetch all the topology information */
+ numa_info = libxl_get_numainfo(ctx, &nr_nodes);
+ if (numa_info == NULL || nr_nodes == 0) {
+ virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+ _("libxl_get_numainfo failed"));
+ goto cleanup;
+ } else {
+ cpu_topo = libxl_get_cpu_topology(ctx, &nr_cpus);
+ if (cpu_topo == NULL || nr_cpus == 0) {
+ virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+ _("libxl_get_cpu_topology failed"));
+ goto cleanup;
+ }
+ }
+
+ if (VIR_ALLOC_N(cpus, nr_nodes) < 0)
+ goto cleanup;
+
+ if (VIR_ALLOC_N(nr_cpus_node, nr_nodes) < 0)
+ goto cleanup;
+
+ /* For each node, prepare a list of CPUs belonging to that node */
+ for (i = 0; i < nr_cpus; i++) {
+ int node = cpu_topo[i].node;
+
+ if (cpu_topo[i].core == LIBXL_CPUTOPOLOGY_INVALID_ENTRY)
+ continue;
+
+ nr_cpus_node[node]++;
+
+ if (nr_cpus_node[node] == 1) {
+ if (VIR_ALLOC(cpus[node]) < 0)
+ goto cleanup;
+ } else {
+ if (VIR_REALLOC_N(cpus[node], nr_cpus_node[node]) < 0)
+ goto cleanup;
+ }
+
+ /* Mapping between what libxl tells and what libvirt wants */
+ cpus[node][nr_cpus_node[node]-1].id = i;
+ cpus[node][nr_cpus_node[node]-1].socket_id = cpu_topo[i].socket;
+ cpus[node][nr_cpus_node[node]-1].core_id = cpu_topo[i].core;
+ /* Allocate the siblings maps. We will be filling them later */
+ cpus[node][nr_cpus_node[node]-1].siblings = virBitmapNew(nr_cpus);
+ if (!cpus[node][nr_cpus_node[node]-1].siblings) {
+ virReportOOMError();
+ goto cleanup;
+ }
+ }
+
+ /* Let's now populate the siblings bitmaps */
+ for (i = 0; i < nr_cpus; i++) {
+ int node = cpu_topo[i].node;
+ size_t j;
+
+ if (cpu_topo[i].core == LIBXL_CPUTOPOLOGY_INVALID_ENTRY)
+ continue;
+
+ for (j = 0; j < nr_cpus_node[node]; j++) {
+ if (cpus[node][j].socket_id == cpu_topo[i].socket &&
+ cpus[node][j].core_id == cpu_topo[i].core)
+ ignore_value(virBitmapSetBit(cpus[node][j].siblings, i));
+ }
+ }
+
+ for (i = 0; i < nr_nodes; i++) {
+ if (numa_info[i].size == LIBXL_NUMAINFO_INVALID_ENTRY)
+ continue;
+
+ if (virCapabilitiesAddHostNUMACell(caps, i, nr_cpus_node[i],
+ numa_info[i].size / 1024,
+ cpus[i]) < 0) {
+ virCapabilitiesClearHostNUMACellCPUTopology(cpus[i],
+ nr_cpus_node[i]);
+ goto cleanup;
+ }
+
+ /* This is safe, as the CPU list is now stored in the NUMA cell */
+ cpus[i] = NULL;
+ }
+
+ ret = 0;
+
+ cleanup:
+ if (ret != 0) {
+ /* Something went wrong: deallocate everything and unref caps */
+ virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+ _("libxenlight failed to build the NUMA topology"));
+
+ for (i = 0; i < nr_nodes; i++)
+ VIR_FREE(cpus[i]);
+ virCapabilitiesFreeNUMAInfo(caps);
+ }
+
+ VIR_FREE(cpus);
+ VIR_FREE(nr_cpus_node);
+ libxl_cputopology_list_free(cpu_topo, nr_cpus);
+ libxl_numainfo_list_free(numa_info, nr_nodes);
+
+ return ret;
+}
+
+static int
libxlCapsInitGuests(libxl_ctx *ctx, virCapsPtr caps)
{
const libxl_version_info *ver_info;
@@ -880,6 +993,9 @@ libxlMakeCapabilities(libxl_ctx *ctx)
if (libxlCapsInitHost(ctx, caps) < 0)
goto error;
+ if (libxlCapsInitNuma(ctx, caps) < 0)
+ goto error;
+
if (libxlCapsInitGuests(ctx, caps) < 0)
goto error;
--
1.8.1.4