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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: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Dmitry Rogozhkin <dmitry.v.rogozhkin@intel.com>
Tested-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20171123123432.25035-2-tvrtko.ursulin@linux.intel.com
This commit is contained in:
Tvrtko Ursulin 2017-11-23 12:34:32 +00:00
parent 141a0895d5
commit 0426c04654
1 changed files with 4 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
drivers/gpu/drm/i915/i915_pmu.c
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@ -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;