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authorMax Krasnyansky <maxk@qualcomm.com>2008-05-29 11:17:01 -0700
committerIngo Molnar <mingo@elte.hu>2008-06-06 15:25:00 +0200
commit5c8e1ed1d204a6770ca2854cd3b3597070fe7e5a (patch)
tree72a2bb4394d1f0b8492ea9566990a39ca597b840 /kernel
parent1100ac91b6af02d8639d518fad5b434b1bf44ed6 (diff)
sched: CPU hotplug events must not destroy scheduler domains created by the cpusets
First issue is not related to the cpusets. We're simply leaking doms_cur. It's allocated in arch_init_sched_domains() which is called for every hotplug event. So we just keep reallocation doms_cur without freeing it. I introduced free_sched_domains() function that cleans things up. Second issue is that sched domains created by the cpusets are completely destroyed by the CPU hotplug events. For all CPU hotplug events scheduler attaches all CPUs to the NULL domain and then puts them all into the single domain thereby destroying domains created by the cpusets (partition_sched_domains). The solution is simple, when cpusets are enabled scheduler should not create default domain and instead let cpusets do that. Which is exactly what the patch does. Signed-off-by: Max Krasnyansky <maxk@qualcomm.com> Cc: pj@sgi.com Cc: menage@google.com Cc: rostedt@goodmis.org Cc: mingo@elte.hu Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/cpuset.c6
-rw-r--r--kernel/sched.c22
2 files changed, 28 insertions, 0 deletions
diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 86ea9e34e326..6090d18b58a9 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -1886,6 +1886,12 @@ static void common_cpu_mem_hotplug_unplug(void)
top_cpuset.mems_allowed = node_states[N_HIGH_MEMORY];
scan_for_empty_cpusets(&top_cpuset);
+ /*
+ * Scheduler destroys domains on hotplug events.
+ * Rebuild them based on the current settings.
+ */
+ rebuild_sched_domains();
+
cgroup_unlock();
}
diff --git a/kernel/sched.c b/kernel/sched.c
index f0ed81b71282..1ddb0a8c7976 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -7293,6 +7293,18 @@ void __attribute__((weak)) arch_update_cpu_topology(void)
}
/*
+ * Free current domain masks.
+ * Called after all cpus are attached to NULL domain.
+ */
+static void free_sched_domains(void)
+{
+ ndoms_cur = 0;
+ if (doms_cur != &fallback_doms)
+ kfree(doms_cur);
+ doms_cur = &fallback_doms;
+}
+
+/*
* Set up scheduler domains and groups. Callers must hold the hotplug lock.
* For now this just excludes isolated cpus, but could be used to
* exclude other special cases in the future.
@@ -7439,6 +7451,7 @@ int arch_reinit_sched_domains(void)
get_online_cpus();
mutex_lock(&sched_domains_mutex);
detach_destroy_domains(&cpu_online_map);
+ free_sched_domains();
err = arch_init_sched_domains(&cpu_online_map);
mutex_unlock(&sched_domains_mutex);
put_online_cpus();
@@ -7524,6 +7537,7 @@ static int update_sched_domains(struct notifier_block *nfb,
case CPU_DOWN_PREPARE:
case CPU_DOWN_PREPARE_FROZEN:
detach_destroy_domains(&cpu_online_map);
+ free_sched_domains();
return NOTIFY_OK;
case CPU_UP_CANCELED:
@@ -7542,8 +7556,16 @@ static int update_sched_domains(struct notifier_block *nfb,
return NOTIFY_DONE;
}
+#ifndef CONFIG_CPUSETS
+ /*
+ * Create default domain partitioning if cpusets are disabled.
+ * Otherwise we let cpusets rebuild the domains based on the
+ * current setup.
+ */
+
/* The hotplug lock is already held by cpu_up/cpu_down */
arch_init_sched_domains(&cpu_online_map);
+#endif
return NOTIFY_OK;
}

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