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authorIgor Mammedov <imammedo@redhat.com>2015-03-19 17:09:21 +0000
committerEduardo Habkost <ehabkost@redhat.com>2015-03-19 16:12:09 -0300
commit57924bcd87cb03cc21ebd7efed880d16ca048dce (patch)
tree6c64141a2db6ef60b6445a204d633dbb7608063a /numa.c
parent3ef7197505e483e2f28c5fbd6ed54b4061221200 (diff)
downloadqemu-arm-57924bcd87cb03cc21ebd7efed880d16ca048dce.tar.gz
numa: introduce machine callback for VCPU to node mapping
Current default round-robin way of distributing VCPUs among NUMA nodes might be wrong in case on multi-core/threads CPUs. Making guests confused wrt topology where cores from the same socket are on different nodes. Allow a machine to override default mapping by providing MachineClass::cpu_index_to_socket_id() callback which would allow it group VCPUs from a socket on the same NUMA node. Signed-off-by: Igor Mammedov <imammedo@redhat.com> Reviewed-by: Andreas Färber <afaerber@suse.de> Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Diffstat (limited to 'numa.c')
-rw-r--r--numa.c18
1 files changed, 13 insertions, 5 deletions
diff --git a/numa.c b/numa.c
index 518aedd88e..fe74e1eeaf 100644
--- a/numa.c
+++ b/numa.c
@@ -202,7 +202,7 @@ static void validate_numa_cpus(void)
}
}
-void parse_numa_opts(void)
+void parse_numa_opts(MachineClass *mc)
{
int i;
@@ -270,13 +270,21 @@ void parse_numa_opts(void)
break;
}
}
- /* assigning the VCPUs round-robin is easier to implement, guest OSes
- * must cope with this anyway, because there are BIOSes out there in
- * real machines which also use this scheme.
+ /* Historically VCPUs were assigned in round-robin order to NUMA
+ * nodes. However it causes issues with guest not handling it nice
+ * in case where cores/threads from a multicore CPU appear on
+ * different nodes. So allow boards to override default distribution
+ * rule grouping VCPUs by socket so that VCPUs from the same socket
+ * would be on the same node.
*/
if (i == nb_numa_nodes) {
for (i = 0; i < max_cpus; i++) {
- set_bit(i, numa_info[i % nb_numa_nodes].node_cpu);
+ unsigned node_id = i % nb_numa_nodes;
+ if (mc->cpu_index_to_socket_id) {
+ node_id = mc->cpu_index_to_socket_id(i) % nb_numa_nodes;
+ }
+
+ set_bit(i, numa_info[node_id].node_cpu);
}
}