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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
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>
-rw-r--r--include/hw/boards.h5
-rw-r--r--include/sysemu/numa.h3
-rw-r--r--numa.c18
-rw-r--r--vl.c2
4 files changed, 21 insertions, 7 deletions
diff --git a/include/hw/boards.h b/include/hw/boards.h
index 1feea2b176..78838d13d4 100644
--- a/include/hw/boards.h
+++ b/include/hw/boards.h
@@ -82,6 +82,10 @@ bool machine_mem_merge(MachineState *machine);
* of HotplugHandler object, which handles hotplug operation
* for a given @dev. It may return NULL if @dev doesn't require
* any actions to be performed by hotplug handler.
+ * @cpu_index_to_socket_id:
+ * used to provide @cpu_index to socket number mapping, allowing
+ * a machine to group CPU threads belonging to the same socket/package
+ * Returns: socket number given cpu_index belongs to.
*/
struct MachineClass {
/*< private >*/
@@ -118,6 +122,7 @@ struct MachineClass {
HotplugHandler *(*get_hotplug_handler)(MachineState *machine,
DeviceState *dev);
+ unsigned (*cpu_index_to_socket_id)(unsigned cpu_index);
};
/**
diff --git a/include/sysemu/numa.h b/include/sysemu/numa.h
index 5633b856a8..6523b4d7f9 100644
--- a/include/sysemu/numa.h
+++ b/include/sysemu/numa.h
@@ -6,6 +6,7 @@
#include "qemu/option.h"
#include "sysemu/sysemu.h"
#include "sysemu/hostmem.h"
+#include "hw/boards.h"
extern int nb_numa_nodes; /* Number of NUMA nodes */
@@ -16,7 +17,7 @@ typedef struct node_info {
bool present;
} NodeInfo;
extern NodeInfo numa_info[MAX_NODES];
-void parse_numa_opts(void);
+void parse_numa_opts(MachineClass *mc);
void numa_post_machine_init(void);
void query_numa_node_mem(uint64_t node_mem[]);
extern QemuOptsList qemu_numa_opts;
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);
}
}
diff --git a/vl.c b/vl.c
index 69617d640a..75ec292216 100644
--- a/vl.c
+++ b/vl.c
@@ -4170,7 +4170,7 @@ int main(int argc, char **argv, char **envp)
default_drive(default_floppy, snapshot, IF_FLOPPY, 0, FD_OPTS);
default_drive(default_sdcard, snapshot, IF_SD, 0, SD_OPTS);
- parse_numa_opts();
+ parse_numa_opts(machine_class);
if (qemu_opts_foreach(qemu_find_opts("mon"), mon_init_func, NULL, 1) != 0) {
exit(1);