perfcounters: enable lowlevel pmc code to schedule counters
Allow lowlevel ->enable() op to return an error if a counter can not be
added. This can be used to handle counter constraints.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c
index f1110ac..2e73929 100644
--- a/kernel/perf_counter.c
+++ b/kernel/perf_counter.c
@@ -355,21 +355,25 @@
cpuctx->task_ctx = NULL;
}
-static void
+static int
counter_sched_in(struct perf_counter *counter,
struct perf_cpu_context *cpuctx,
struct perf_counter_context *ctx,
int cpu)
{
if (counter->state == PERF_COUNTER_STATE_OFF)
- return;
+ return 0;
- counter->hw_ops->enable(counter);
+ if (counter->hw_ops->enable(counter))
+ return -EAGAIN;
+
counter->state = PERF_COUNTER_STATE_ACTIVE;
counter->oncpu = cpu; /* TODO: put 'cpu' into cpuctx->cpu */
cpuctx->active_oncpu++;
ctx->nr_active++;
+
+ return 0;
}
static int
@@ -378,20 +382,38 @@
struct perf_counter_context *ctx,
int cpu)
{
- struct perf_counter *counter;
- int was_group = 0;
+ struct perf_counter *counter, *partial_group;
+ int ret = 0;
- counter_sched_in(group_counter, cpuctx, ctx, cpu);
+ if (counter_sched_in(group_counter, cpuctx, ctx, cpu))
+ return -EAGAIN;
/*
* Schedule in siblings as one group (if any):
*/
list_for_each_entry(counter, &group_counter->sibling_list, list_entry) {
- counter_sched_in(counter, cpuctx, ctx, cpu);
- was_group = 1;
+ if (counter_sched_in(counter, cpuctx, ctx, cpu)) {
+ partial_group = counter;
+ goto group_error;
+ }
+ ret = -EAGAIN;
}
- return was_group;
+ return ret;
+
+group_error:
+ /*
+ * Groups can be scheduled in as one unit only, so undo any
+ * partial group before returning:
+ */
+ list_for_each_entry(counter, &group_counter->sibling_list, list_entry) {
+ if (counter == partial_group)
+ break;
+ counter_sched_out(counter, cpuctx, ctx);
+ }
+ counter_sched_out(group_counter, cpuctx, ctx);
+
+ return -EAGAIN;
}
/*
@@ -416,9 +438,6 @@
spin_lock(&ctx->lock);
list_for_each_entry(counter, &ctx->counter_list, list_entry) {
- if (ctx->nr_active == cpuctx->max_pertask)
- break;
-
/*
* Listen to the 'cpu' scheduling filter constraint
* of counters:
@@ -856,8 +875,9 @@
.poll = perf_poll,
};
-static void cpu_clock_perf_counter_enable(struct perf_counter *counter)
+static int cpu_clock_perf_counter_enable(struct perf_counter *counter)
{
+ return 0;
}
static void cpu_clock_perf_counter_disable(struct perf_counter *counter)
@@ -913,11 +933,13 @@
task_clock_perf_counter_update(counter, now);
}
-static void task_clock_perf_counter_enable(struct perf_counter *counter)
+static int task_clock_perf_counter_enable(struct perf_counter *counter)
{
u64 now = task_clock_perf_counter_val(counter, 0);
atomic64_set(&counter->hw.prev_count, now);
+
+ return 0;
}
static void task_clock_perf_counter_disable(struct perf_counter *counter)
@@ -960,12 +982,14 @@
page_faults_perf_counter_update(counter);
}
-static void page_faults_perf_counter_enable(struct perf_counter *counter)
+static int page_faults_perf_counter_enable(struct perf_counter *counter)
{
/*
* page-faults is a per-task value already,
* so we dont have to clear it on switch-in.
*/
+
+ return 0;
}
static void page_faults_perf_counter_disable(struct perf_counter *counter)
@@ -1006,12 +1030,14 @@
context_switches_perf_counter_update(counter);
}
-static void context_switches_perf_counter_enable(struct perf_counter *counter)
+static int context_switches_perf_counter_enable(struct perf_counter *counter)
{
/*
* ->nvcsw + curr->nivcsw is a per-task value already,
* so we dont have to clear it on switch-in.
*/
+
+ return 0;
}
static void context_switches_perf_counter_disable(struct perf_counter *counter)
@@ -1050,12 +1076,14 @@
cpu_migrations_perf_counter_update(counter);
}
-static void cpu_migrations_perf_counter_enable(struct perf_counter *counter)
+static int cpu_migrations_perf_counter_enable(struct perf_counter *counter)
{
/*
* se.nr_migrations is a per-task value already,
* so we dont have to clear it on switch-in.
*/
+
+ return 0;
}
static void cpu_migrations_perf_counter_disable(struct perf_counter *counter)