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Commit 55baa2f8 authored by Hendrik Brueckner's avatar Hendrik Brueckner Committed by Martin Schwidefsky
Browse files

s390/perf: Improve PMU selection for PERF_COUNT_HW_CPU_CYCLES events 



The cpum_cf (counter facility) PMU does not support sampling events.
With cpum_sf (sampling facility), a PMU for sampling CPU cycles is
available.

Make cpum_sf the "default" PMU for PERF_COUNT_HW_CPU_CYCLES sampling
events but use the more precise cpum_cf PMU for non-sampling events.

Signed-off-by: default avatarHendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 8c069ff4

arch/s390/kernel/perf_cpum_sf.c

+22 −4
Original line number Original line Diff line number Diff line
@@ -468,11 +468,29 @@ static int cpumsf_pmu_event_init(struct perf_event *event) 
{

{

	int err;

	int err;





	if (event->attr.type != PERF_TYPE_RAW)

	/* No support for taken branch sampling */

		return -ENOENT;

	if (has_branch_stack(event))

		return -EOPNOTSUPP;





	switch (event->attr.type) {

	case PERF_TYPE_RAW:

		if (event->attr.config != PERF_EVENT_CPUM_SF)

		if (event->attr.config != PERF_EVENT_CPUM_SF)

			return -ENOENT;

			return -ENOENT;

		break;

	case PERF_TYPE_HARDWARE:

		/* Support sampling of CPU cycles in addition to the

		 * counter facility.  However, the counter facility

		 * is more precise and, hence, restrict this PMU to

		 * sampling events only.

		 */

		if (event->attr.config != PERF_COUNT_HW_CPU_CYCLES)

			return -ENOENT;

		if (!is_sampling_event(event))

			return -ENOENT;

		break;

	default:

		return -ENOENT;

	}





	if (event->cpu >= nr_cpumask_bits ||

	if (event->cpu >= nr_cpumask_bits ||

	    (event->cpu >= 0 && !cpu_online(event->cpu)))

	    (event->cpu >= 0 && !cpu_online(event->cpu)))