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authorPeter Zijlstra <a.p.zijlstra@chello.nl>2009-06-19 13:22:51 +0200
committerIngo Molnar <mingo@elte.hu>2009-06-19 13:43:12 +0200
commite5289d4a181fb6c0b7a7607649af2ffdc491335c (patch)
tree6c9e9ab46a29c538e4c505d3d3cd135265db08a2 /kernel/perf_counter.c
parentf5970550d5ccf90453cbd7d260370ea99d1f6513 (diff)
perf_counter: Simplify and fix task migration counting
The task migrations counter was causing rare and hard to decypher memory corruptions under load. After a day of debugging and bisection we found that the problem was introduced with: 3f731ca: perf_counter: Fix cpu migration counter Turning them off fixes the crashes. Incidentally, the whole perf_counter_task_migration() logic can be done simpler as well, by injecting a proper sw-counter event. This cleanup also fixed the crashes. The precise failure mode is not completely clear yet, but we are clearly not unhappy about having a fix ;-) Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Mike Galbraith <efault@gmx.de> Cc: Paul Mackerras <paulus@samba.org> Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> LKML-Reference: <new-submission> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/perf_counter.c')
-rw-r--r--kernel/perf_counter.c23
1 files changed, 1 insertions, 22 deletions
diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c
index 7e9108efd30..8d4f0dd41c2 100644
--- a/kernel/perf_counter.c
+++ b/kernel/perf_counter.c
@@ -124,7 +124,7 @@ void perf_enable(void)
static void get_ctx(struct perf_counter_context *ctx)
{
- atomic_inc(&ctx->refcount);
+ WARN_ON(!atomic_inc_not_zero(&ctx->refcount));
}
static void free_ctx(struct rcu_head *head)
@@ -3467,27 +3467,6 @@ static const struct pmu perf_ops_task_clock = {
.read = task_clock_perf_counter_read,
};
-/*
- * Software counter: cpu migrations
- */
-void perf_counter_task_migration(struct task_struct *task, int cpu)
-{
- struct perf_cpu_context *cpuctx = &per_cpu(perf_cpu_context, cpu);
- struct perf_counter_context *ctx;
-
- perf_swcounter_ctx_event(&cpuctx->ctx, PERF_TYPE_SOFTWARE,
- PERF_COUNT_SW_CPU_MIGRATIONS,
- 1, 1, NULL, 0);
-
- ctx = perf_pin_task_context(task);
- if (ctx) {
- perf_swcounter_ctx_event(ctx, PERF_TYPE_SOFTWARE,
- PERF_COUNT_SW_CPU_MIGRATIONS,
- 1, 1, NULL, 0);
- perf_unpin_context(ctx);
- }
-}
-
#ifdef CONFIG_EVENT_PROFILE
void perf_tpcounter_event(int event_id)
{