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powerpc/perf: Don't use perf_hw_context for trace IMC PMU 

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 should only be used for CPU PMU.
See commit 2665784850 ("perf/core: Verify we have a single
perf_hw_context PMU").

So for trace_imc, even though it is per thread PMU, it is preferred to
use sw_context in order to be able to do application level monitoring.
Hence change the task_ctx_nr to use perf_sw_context.

Fixes: 012ae24484 ("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>
[mpe: Update subject & incorporate notes into change log, reflow comment]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220202041837.65968-1-atrajeev@linux.vnet.ibm.com
This commit is contained in:
Athira Rajeev 2022-02-02 09:48:37 +05:30 committed by Michael Ellerman
parent d4be60fe66
commit 0198322379
1 changed files with 5 additions and 1 deletions
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6
arch/powerpc/perf/imc-pmu.c
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@ -1457,7 +1457,11 @@ static int trace_imc_event_init(struct perf_event *event)
event->hw.idx = -1; 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; event->destroy = reset_global_refc;
return 0; return 0;
} }