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Commit 0426c046 authored by Tvrtko Ursulin's avatar Tvrtko Ursulin
Browse files

drm/i915/pmu: Only allow running on a single CPU 



We do two things, both of which are purely to simplify and clarify the
implementation:

1.

Simplify the CPU online callback so it is more obvious that the purpose
there is to set a single CPU mask bit for the first CPU which comes
online. Using cpumask_weight for this reads more obvious than the trick
with cpumask_and_any.

2.

Modify the event init so that events can be created only on a single CPU.

This removes looking at the requested CPU thread siblings, and only allows
creating on the current active CPU.

Signed-off-by: default avatarTvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Dmitry Rogozhkin <dmitry.v.rogozhkin@intel.com>
Tested-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20171123123432.25035-2-tvrtko.ursulin@linux.intel.com
parent 141a0895

drivers/gpu/drm/i915/i915_pmu.c

+4 −8
Original line number Diff line number Diff line
@@ -344,7 +344,7 @@ static int i915_pmu_event_init(struct perf_event *event) 
{

	struct drm_i915_private *i915 =

		container_of(event->pmu, typeof(*i915), pmu.base);

	int cpu, ret;

	int ret;



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

		return -ENOENT;
@@ -359,9 +359,8 @@ static int i915_pmu_event_init(struct perf_event *event) 
	if (event->cpu < 0)

		return -EINVAL;



	cpu = cpumask_any_and(&i915_pmu_cpumask,

			      topology_sibling_cpumask(event->cpu));

	if (cpu >= nr_cpu_ids)

	/* only allow running on one cpu at a time */

	if (!cpumask_test_cpu(event->cpu, &i915_pmu_cpumask))

		return -ENODEV;



	if (is_engine_event(event)) {
@@ -396,7 +395,6 @@ static int i915_pmu_event_init(struct perf_event *event) 
	if (ret)

		return ret;



	event->cpu = cpu;

	if (!event->parent)

		event->destroy = i915_pmu_event_destroy;
@@ -773,13 +771,11 @@ static const struct attribute_group *i915_pmu_attr_groups[] = { 
static int i915_pmu_cpu_online(unsigned int cpu, struct hlist_node *node)

{

	struct i915_pmu *pmu = hlist_entry_safe(node, typeof(*pmu), node);

	unsigned int target;



	GEM_BUG_ON(!pmu->base.event_init);



	target = cpumask_any_and(&i915_pmu_cpumask, &i915_pmu_cpumask);

	/* Select the first online CPU as a designated reader. */

	if (target >= nr_cpu_ids)

	if (!cpumask_weight(&i915_pmu_cpumask))

		cpumask_set_cpu(cpu, &i915_pmu_cpumask);



	return 0;