perf/x86: Ensure perf_sched_cb_{inc,dec}() is only called from pmu::{add,del}()
Currently perf_sched_cb_{inc,dec}() are called from
pmu::{start,stop}(), which has the problem that this can happen from
NMI context, this is making it hard to optimize perf_pmu_sched_task().
Furthermore, we really only need this accounting on pmu::{add,del}(),
so doing it from pmu::{start,stop}() is doing more work than we really
need.
Introduce x86_pmu::{add,del}() and wire up the LBR and PEBS.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index d0efb5c..18a1acf8 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -1201,6 +1201,9 @@
* If group events scheduling transaction was started,
* skip the schedulability test here, it will be performed
* at commit time (->commit_txn) as a whole.
+ *
+ * If commit fails, we'll call ->del() on all events
+ * for which ->add() was called.
*/
if (cpuc->txn_flags & PERF_PMU_TXN_ADD)
goto done_collect;
@@ -1223,6 +1226,14 @@
cpuc->n_added += n - n0;
cpuc->n_txn += n - n0;
+ if (x86_pmu.add) {
+ /*
+ * This is before x86_pmu_enable() will call x86_pmu_start(),
+ * so we enable LBRs before an event needs them etc..
+ */
+ x86_pmu.add(event);
+ }
+
ret = 0;
out:
return ret;
@@ -1346,7 +1357,7 @@
event->hw.flags &= ~PERF_X86_EVENT_COMMITTED;
/*
- * If we're called during a txn, we don't need to do anything.
+ * If we're called during a txn, we only need to undo x86_pmu.add.
* The events never got scheduled and ->cancel_txn will truncate
* the event_list.
*
@@ -1354,7 +1365,7 @@
* an event added during that same TXN.
*/
if (cpuc->txn_flags & PERF_PMU_TXN_ADD)
- return;
+ goto do_del;
/*
* Not a TXN, therefore cleanup properly.
@@ -1384,6 +1395,15 @@
--cpuc->n_events;
perf_event_update_userpage(event);
+
+do_del:
+ if (x86_pmu.del) {
+ /*
+ * This is after x86_pmu_stop(); so we disable LBRs after any
+ * event can need them etc..
+ */
+ x86_pmu.del(event);
+ }
}
int x86_pmu_handle_irq(struct pt_regs *regs)