[libvirt] [PATCH v2 1/3] libxl: implement NUMA capabilities reporting
Dario Faggioli
dario.faggioli at citrix.com
Fri Jul 5 01:25:03 UTC 2013
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 at 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>
....
Signed-off-by: Dario Faggioli <dario.faggioli at citrix.com>
---
Changes from v1:
* fixed a typo in the commit message, as requested during review;
* fixed coding style (one function parameters per line and no spaces
between variable definitions), as requested during review;
* avoid zero-filling memory after VIR_ALLOC_N(), since it does that
already, as requested during review;
* improved out of memory error reporting, as requested during review;
* libxlMakeNumaCapabilities() created, accommodating all the NUMA
related additions, instead of having them within
libxlMakeCapabilitiesInternal(), as suggested during review.
---
src/libxl/libxl_conf.c | 141 ++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 140 insertions(+), 1 deletion(-)
diff --git a/src/libxl/libxl_conf.c b/src/libxl/libxl_conf.c
index e170357..7515995 100644
--- a/src/libxl/libxl_conf.c
+++ b/src/libxl/libxl_conf.c
@@ -161,6 +161,115 @@ libxlBuildCapabilities(virArch hostarch,
}
static virCapsPtr
+libxlMakeNumaCapabilities(libxl_numainfo *numa_info,
+ int nr_nodes,
+ libxl_cputopology *cpu_topo,
+ int nr_cpus,
+ virCapsPtr caps)
+{
+ virCapsHostNUMACellCPUPtr *cpus = NULL;
+ int *nr_cpus_node = NULL;
+ bool numa_failed = false;
+ int i;
+
+ if (VIR_ALLOC_N(cpus, nr_nodes)) {
+ virReportOOMError();
+ return caps;
+ }
+
+ if (VIR_ALLOC_N(nr_cpus_node, nr_nodes)) {
+ VIR_FREE(cpus);
+ virReportOOMError();
+ return caps;
+ }
+
+ /* 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) {
+ virReportOOMError();
+ numa_failed = true;
+ goto cleanup;
+ }
+ }
+ else {
+ if (VIR_REALLOC_N(cpus[node], nr_cpus_node[node]) < 0) {
+ virReportOOMError();
+ numa_failed = true;
+ 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();
+ numa_failed = true;
+ goto cleanup;
+ }
+ }
+
+ /* Let's now populate the siblings bitmaps */
+ for (i = 0; i < nr_cpus; i++) {
+ int j, node = cpu_topo[i].node;
+
+ if (cpu_topo[i].core == LIBXL_CPUTOPOLOGY_INVALID_ENTRY)
+ continue;
+
+ for (j = 0; j < nr_cpus_node[node]; j++) {
+ if (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]);
+ numa_failed = true;
+ goto cleanup;
+ }
+
+ /* This is safe, as the CPU list is now stored in the NUMA cell */
+ cpus[i] = NULL;
+ }
+
+ cleanup:
+
+ if (numa_failed) {
+ /* Looks like something went wrong. Well, that's bad, but probably
+ * not enough to break the whole driver, so we log and carry on */
+ for (i = 0; i < nr_nodes; i++) {
+ VIR_FREE(cpus[i]);
+ }
+ VIR_WARN("Failed to retrieve and build host NUMA topology properly,\n"
+ "disabling NUMA capabilities");
+ virCapabilitiesFreeNUMAInfo(caps);
+ }
+
+ VIR_FREE(cpus);
+ VIR_FREE(nr_cpus_node);
+
+ return caps;
+}
+
+static virCapsPtr
libxlMakeCapabilitiesInternal(virArch hostarch,
libxl_physinfo *phy_info,
char *capabilities)
@@ -772,7 +881,11 @@ libxlMakeCapabilities(libxl_ctx *ctx)
{
int err;
libxl_physinfo phy_info;
+ libxl_numainfo *numa_info = NULL;
+ libxl_cputopology *cpu_topo = NULL;
const libxl_version_info *ver_info;
+ int nr_nodes = 0, nr_cpus = 0;
+ virCapsPtr caps;
err = regcomp(&xen_cap_rec, xen_cap_re, REG_EXTENDED);
if (err != 0) {
@@ -796,9 +909,35 @@ libxlMakeCapabilities(libxl_ctx *ctx)
return NULL;
}
- return libxlMakeCapabilitiesInternal(virArchFromHost(),
+ /* Let's try to fetch NUMA info, but it is not critical if we fail */
+ numa_info = libxl_get_numainfo(ctx, &nr_nodes);
+ if (numa_info == NULL)
+ VIR_WARN("libxl_get_numainfo failed to retrieve NUMA data");
+ else {
+ /* If the above failed, we'd have no NUMa caps anyway! */
+ cpu_topo = libxl_get_cpu_topology(ctx, &nr_cpus);
+ if (cpu_topo == NULL) {
+ VIR_WARN("libxl_get_cpu_topology failed to retrieve topology");
+ libxl_numainfo_list_free(numa_info, nr_nodes);
+ }
+ }
+
+ caps = libxlMakeCapabilitiesInternal(virArchFromHost(),
&phy_info,
ver_info->capabilities);
+
+ /* Add topology information to caps, if available */
+ if (numa_info && cpu_topo)
+ caps = libxlMakeNumaCapabilities(numa_info,
+ nr_nodes,
+ cpu_topo,
+ nr_cpus,
+ caps);
+
+ libxl_cputopology_list_free(cpu_topo, nr_cpus);
+ libxl_numainfo_list_free(numa_info, nr_nodes);
+
+ return caps;
}
int
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