On 14/12/2022 11:52 am, Ravi Bangoria wrote:
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 7f04f995c975..f671b1a9a691 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -12674,12 +12674,14 @@ SYSCALL_DEFINE5(perf_event_open,
* @attr: attributes of the counter to create
* @cpu: cpu in which the counter is bound
* @task: task to profile (NULL for percpu)
+ * @group_leader: event group leader
* @overflow_handler: callback to trigger when we hit the event
* @context: context data could be used in overflow_handler callback
*/
struct perf_event *
perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu,
struct task_struct *task,
+ struct perf_event *group_leader,
perf_overflow_handler_t overflow_handler,
void *context)
{
@@ -12694,7 +12696,7 @@ perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu,
if (attr->aux_output)
return ERR_PTR(-EINVAL);
- event = perf_event_alloc(attr, cpu, task, NULL, NULL,
+ event = perf_event_alloc(attr, cpu, task, group_leader, NULL,
overflow_handler, context, -1);
Grouping involves lot of complexities. Setting group_leader won't be sufficient.
Please see perf_event_open() syscall code for more detail.
Thanks,
Ravi
This is the main reason why the RFC tag is added. More detailed professional
reviews is encouraged.
AFAI, there does exist a number of code gaps here to support grouped events in
the kernel,
but there are also opportunities, as there may be other new use cases bringing
innovation.
I have to confirm this idea with maintainers first, the alternative is to create
yet another special
perf_event similar to PMC_IDX_FIXED_VLBR, which schedules perf_metrics MSR for
KVM stuff.
PeterZ, any input ?
