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authorPaul Mackerras <paulus@samba.org>2009-06-02 07:05:16 -0400
committerIngo Molnar <mingo@elte.hu>2009-06-02 07:10:54 -0400
commitf38b082081bf69a06fffb8b32a175999e2320c5b (patch)
tree08a26857c77b11a97871b3e1e06ec588033f7cf3 /kernel
parent10a2825514a988225ac2e336c7a9502c4ca57c39 (diff)
perf_counter: Initialize per-cpu context earlier on cpu up
This arranges for perf_counter's notifier for cpu hotplug operations to be called earlier than the migration notifier in sched.c by increasing its priority to 20, compared to the 10 for the migration notifier. The reason for doing this is that a subsequent commit to convert the cpu migration counter to use the generic swcounter infrastructure will add a call into the perf_counter subsystem when tasks get migrated. Therefore the perf_counter subsystem needs a chance to initialize its per-cpu data for the new cpu before it can get called from the migration code. This also adds a comment to the migration notifier noting that its priority needs to be lower than that of the perf_counter notifier. Signed-off-by: Paul Mackerras <paulus@samba.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <18981.1900.792795.836858@cargo.ozlabs.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/perf_counter.c4
-rw-r--r--kernel/sched.c6
2 files changed, 8 insertions, 2 deletions
diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c
index df319c48c52b..8d2653f137e9 100644
--- a/kernel/perf_counter.c
+++ b/kernel/perf_counter.c
@@ -3902,8 +3902,12 @@ perf_cpu_notify(struct notifier_block *self, unsigned long action, void *hcpu)
3902 return NOTIFY_OK; 3902 return NOTIFY_OK;
3903} 3903}
3904 3904
3905/*
3906 * This has to have a higher priority than migration_notifier in sched.c.
3907 */
3905static struct notifier_block __cpuinitdata perf_cpu_nb = { 3908static struct notifier_block __cpuinitdata perf_cpu_nb = {
3906 .notifier_call = perf_cpu_notify, 3909 .notifier_call = perf_cpu_notify,
3910 .priority = 20,
3907}; 3911};
3908 3912
3909void __init perf_counter_init(void) 3913void __init perf_counter_init(void)
diff --git a/kernel/sched.c b/kernel/sched.c
index ad079f07c9c8..3226cc132e9f 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -7319,8 +7319,10 @@ migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu)
7319 return NOTIFY_OK; 7319 return NOTIFY_OK;
7320} 7320}
7321 7321
7322/* Register at highest priority so that task migration (migrate_all_tasks) 7322/*
7323 * happens before everything else. 7323 * Register at high priority so that task migration (migrate_all_tasks)
7324 * happens before everything else. This has to be lower priority than
7325 * the notifier in the perf_counter subsystem, though.
7324 */ 7326 */
7325static struct notifier_block __cpuinitdata migration_notifier = { 7327static struct notifier_block __cpuinitdata migration_notifier = {
7326 .notifier_call = migration_call, 7328 .notifier_call = migration_call,