Trace IMC (In-Memory collection counters) in powerpc is
useful for application level profiling. For trace_imc,
presently task context (task_ctx_nr) is set to
perf_hw_context. But perf_hw_context is to be used for
cpu PMU. So for trace_imc, even though it is per thread
PMU, it is preferred to use sw_context inorder to be able
to do application level monitoring. Hence change the
task_ctx_nr to use perf_sw_context.
Fixes: 012ae244845f ("powerpc/perf: Trace imc PMU functions")
Signed-off-by: Athira Rajeev
Reviewed-by: Madhavan Srinivasan
---
Changelog:
v1 -> v2:
Added comment in code on why perf_sw_context is used.
Notes:
trace_imc_event_init currently uses context as
perf_hw_context. But ideally there can only be a single
PMU for perf_hw_context events which is core PMU.
Reference:
commit 26657848502b ("perf/core: Verify we have a single perf_hw_context PMU")
Reason for using "perf_sw_context" instead of invalid_context
is that, task level monitoring is restricted with
invalid_context.
arch/powerpc/perf/imc-pmu.c | 8 +++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/perf/imc-pmu.c b/arch/powerpc/perf/imc-pmu.c
index e106909ff9c3..8fe57601e61d 100644
--- a/arch/powerpc/perf/imc-pmu.c
+++ b/arch/powerpc/perf/imc-pmu.c
@@ -1457,7 +1457,13 @@ static int trace_imc_event_init(struct perf_event *event)
event->hw.idx = -1;
- event->pmu->task_ctx_nr = perf_hw_context;
+ /*
+* There can only be a single PMU for
+* perf_hw_context events which is assigned
+* to core PMU. Hence use "perf_sw_context" for
+* trace_imc.
+*/
+ event->pmu->task_ctx_nr = perf_sw_context;
event->destroy = reset_global_refc;
return 0;
}
--
2.33.0
