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authorNishanth Aravamudan <nacc@linux.vnet.ibm.com>2014-10-10 20:04:49 +0400
committerMichael Ellerman <mpe@ellerman.id.au>2014-10-13 11:16:17 +0400
commit2d73bae12b26db6eba074b70406c707961b6cda9 (patch)
tree99ac1885683491bdeeb0dfb88195580cecddff62 /arch/powerpc
parent2d15b9b479512f05680541acffd9acbbc831a47c (diff)
downloadlinux-2d73bae12b26db6eba074b70406c707961b6cda9.tar.xz
powerpc/numa: Add ability to disable and debug topology updates
We have hit a few customer issues with the topology update code (VPHN and PRRN). It would be nice to be able to debug the notifications coming from the hypervisor in both cases to the LPAR, as well as to disable responding to the notifications at boot-time, to narrow down the source of the problems. Add a basic level of such functionality, similar to the numa= command-line parameter. We already have a toggle in /proc/powerpc/topology_updates that allows run-time enabling/disabling, so the updates can be started at run-time if desired. But the bugs we've run into have occured during boot or very shortly after coming to login, and have resulted in a broken NUMA topology. Signed-off-by: Nishanth Aravamudan <nacc@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch/powerpc')
-rw-r--r--arch/powerpc/mm/numa.c35
1 files changed, 34 insertions, 1 deletions
diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
index 51d707d85b2d..177659050fa0 100644
--- a/arch/powerpc/mm/numa.c
+++ b/arch/powerpc/mm/numa.c
@@ -8,6 +8,8 @@
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
+#define pr_fmt(fmt) "numa: " fmt
+
#include <linux/threads.h>
#include <linux/bootmem.h>
#include <linux/init.h>
@@ -1153,6 +1155,22 @@ static int __init early_numa(char *p)
}
early_param("numa", early_numa);
+static bool topology_updates_enabled = true;
+
+static int __init early_topology_updates(char *p)
+{
+ if (!p)
+ return 0;
+
+ if (!strcmp(p, "off")) {
+ pr_info("Disabling topology updates\n");
+ topology_updates_enabled = false;
+ }
+
+ return 0;
+}
+early_param("topology_updates", early_topology_updates);
+
#ifdef CONFIG_MEMORY_HOTPLUG
/*
* Find the node associated with a hot added memory section for
@@ -1539,6 +1557,9 @@ int arch_update_cpu_topology(void)
struct device *dev;
int weight, new_nid, i = 0;
+ if (!prrn_enabled && !vphn_enabled)
+ return 0;
+
weight = cpumask_weight(&cpu_associativity_changes_mask);
if (!weight)
return 0;
@@ -1592,6 +1613,15 @@ int arch_update_cpu_topology(void)
cpu = cpu_last_thread_sibling(cpu);
}
+ pr_debug("Topology update for the following CPUs:\n");
+ if (cpumask_weight(&updated_cpus)) {
+ for (ud = &updates[0]; ud; ud = ud->next) {
+ pr_debug("cpu %d moving from node %d "
+ "to %d\n", ud->cpu,
+ ud->old_nid, ud->new_nid);
+ }
+ }
+
/*
* In cases where we have nothing to update (because the updates list
* is too short or because the new topology is same as the old one),
@@ -1800,7 +1830,10 @@ static const struct file_operations topology_ops = {
static int topology_update_init(void)
{
- start_topology_update();
+ /* Do not poll for changes if disabled at boot */
+ if (topology_updates_enabled)
+ start_topology_update();
+
if (!proc_create("powerpc/topology_updates", 0644, NULL, &topology_ops))
return -ENOMEM;