Commit 2c9651c3 authored Mar 14, 2019 by Peter Zijlstra Committed by Ingo Molnar Apr 03, 2019

perf/x86: Clear ->event_constraint[] on put



The current code unconditionally clears cpuc->event_constraint[i]
before calling get_event_constraints(.idx=i). The only site that cares
is intel_get_event_constraints() where the c1 load will always be
NULL.

However, always calling get_event_constraints() on all events is
wastefull, most times it will return the exact same result. Therefore
retain the logic in intel_get_event_constraints() and change the
generic code to only clear the constraint on put.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Stephane Eranian <eranian@google.com>
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: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent c090cb70

arch/x86/events/core.c

+3 −1

Original line number	Diff line number	Diff line
		@@ -858,7 +858,6 @@ int x86_schedule_events(struct cpu_hw_events cpuc, int n, int assign)
		x86_pmu.start_scheduling(cpuc);

		for (i = 0, wmin = X86_PMC_IDX_MAX, wmax = 0; i < n; i++) {
		cpuc->event_constraint[i] = NULL;
		c = x86_pmu.get_event_constraints(cpuc, i, cpuc->event_list[i]);
		cpuc->event_constraint[i] = c;

		@@ -948,6 +947,8 @@ int x86_schedule_events(struct cpu_hw_events cpuc, int n, int assign)
		*/
		if (x86_pmu.put_event_constraints)
		x86_pmu.put_event_constraints(cpuc, e);

		cpuc->event_constraint[i] = NULL;
		}
		}

		@@ -1411,6 +1412,7 @@ static void x86_pmu_del(struct perf_event *event, int flags)
		cpuc->event_list[i-1] = cpuc->event_list[i];
		cpuc->event_constraint[i-1] = cpuc->event_constraint[i];
		}
		cpuc->event_constraint[i-1] = NULL;
		--cpuc->n_events;

		perf_event_update_userpage(event);

Admin message