* [PATCH] powerpc/perf: Fix task context setting for trace imc
@ 2021-11-24 2:46 Athira Rajeev
2022-01-19 10:56 ` Michael Ellerman
0 siblings, 1 reply; 2+ messages in thread
From: Athira Rajeev @ 2021-11-24 2:46 UTC (permalink / raw)
To: mpe; +Cc: kjain, maddy, linuxppc-dev, rnsastry
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 <atrajeev@linux.vnet.ibm.com>
Reviewed-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
---
arch/powerpc/perf/imc-pmu.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/powerpc/perf/imc-pmu.c b/arch/powerpc/perf/imc-pmu.c
index e106909ff9c3..f3b3262bdf02 100644
--- a/arch/powerpc/perf/imc-pmu.c
+++ b/arch/powerpc/perf/imc-pmu.c
@@ -1457,7 +1457,7 @@ static int trace_imc_event_init(struct perf_event *event)
event->hw.idx = -1;
- event->pmu->task_ctx_nr = perf_hw_context;
+ event->pmu->task_ctx_nr = perf_sw_context;
event->destroy = reset_global_refc;
return 0;
}
--
2.33.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] powerpc/perf: Fix task context setting for trace imc
2021-11-24 2:46 [PATCH] powerpc/perf: Fix task context setting for trace imc Athira Rajeev
@ 2022-01-19 10:56 ` Michael Ellerman
0 siblings, 0 replies; 2+ messages in thread
From: Michael Ellerman @ 2022-01-19 10:56 UTC (permalink / raw)
To: Athira Rajeev; +Cc: kjain, maddy, linuxppc-dev, rnsastry
Athira Rajeev <atrajeev@linux.vnet.ibm.com> writes:
> 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.
It's not a software event though, so this is not obviously correct.
Can you explain more why this is OK, I guess perf_sw_context is misnamed
these days? And can you add a comment in the code explaining why this
hardware PMU is using perf_sw_context.
cheers
> Fixes: 012ae244845f ("powerpc/perf: Trace imc PMU functions")
> Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
> Reviewed-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
> ---
> arch/powerpc/perf/imc-pmu.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/powerpc/perf/imc-pmu.c b/arch/powerpc/perf/imc-pmu.c
> index e106909ff9c3..f3b3262bdf02 100644
> --- a/arch/powerpc/perf/imc-pmu.c
> +++ b/arch/powerpc/perf/imc-pmu.c
> @@ -1457,7 +1457,7 @@ static int trace_imc_event_init(struct perf_event *event)
>
> event->hw.idx = -1;
>
> - event->pmu->task_ctx_nr = perf_hw_context;
> + event->pmu->task_ctx_nr = perf_sw_context;
> event->destroy = reset_global_refc;
> return 0;
> }
> --
> 2.33.0
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