| Message ID | 1585568332-11934-1-git-send-email-atrajeev@linux.vnet.ibm.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | powerpc/perf: Add documentation around use of "ppc_set_pmu_inuse" in PMU core-book3s | expand |
| Context | Check | Description |
|---|---|---|
| snowpatch_ozlabs/apply_patch | success | Successfully applied on branch powerpc/merge (c6624071c338732402e8c726df6a4074473eaa0e) |
| snowpatch_ozlabs/build-ppc64le | success | Build succeeded |
| snowpatch_ozlabs/build-ppc64be | success | Build succeeded |
| snowpatch_ozlabs/build-ppc64e | success | Build succeeded |
| snowpatch_ozlabs/build-pmac32 | success | Build succeeded |
| snowpatch_ozlabs/checkpatch | success | total: 0 errors, 0 warnings, 0 checks, 22 lines checked |
| snowpatch_ozlabs/needsstable | success | Patch has no Fixes tags |
Hi, Please ignore this version as I messed up with the author information. I am sending a V2 with the proper author name. Thanks Athira > On 30-Mar-2020, at 5:08 PM, Athira Rajeev <atrajeev@linux.vnet.ibm.com> wrote: > > "pmcregs_in_use" flag is part of lppaca (Virtual Process Area), > which is used to indicate whether Performance Monitoring Unit (PMU) and > PMU sprs are in-use and whether should it be saved/restored by > hypervisor. ppc_set_pmu_inuse() is used to set/unset the VPA > flag "pmcregs_in_use". "pmcregs_in_use" flag is set in > "power_pmu_enable" via ppc_set_pmu_inuse(1) and it is unset > when there are no active events (n_events == 0 condition). > > Patch here adds documentation on the ppc_set_pmu_inuse() usage. > > Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com> > Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com> > --- > arch/powerpc/perf/core-book3s.c | 10 ++++++++++ > 1 file changed, 10 insertions(+) > > diff --git a/arch/powerpc/perf/core-book3s.c b/arch/powerpc/perf/core-book3s.c > index 3086055..48bfdc9 100644 > --- a/arch/powerpc/perf/core-book3s.c > +++ b/arch/powerpc/perf/core-book3s.c > @@ -1285,6 +1285,11 @@ static void power_pmu_enable(struct pmu *pmu) > goto out; > > if (cpuhw->n_events == 0) { > + /* > + * Indicate PMU not in-use to Hypervisor. > + * We end-up here via "ctx_sched_out()" from common code and > + * "power_pmu_del()". > + */ > ppc_set_pmu_inuse(0); > goto out; > } > @@ -1341,6 +1346,11 @@ static void power_pmu_enable(struct pmu *pmu) > * Write the new configuration to MMCR* with the freeze > * bit set and set the hardware events to their initial values. > * Then unfreeze the events. > + * ppc_set_pmu_inuse(1): "power_pmu_enable" will unset the > + * "pmcregs_in_use" flag when a previous profiling/sampling session > + * is completed and un-setting of flag will notify the Hypervisor to > + * drop save/restore of PMU sprs. Now that PMU need to be enabled, first > + * set the "pmcregs_in_use" flag in VPA. > */ > ppc_set_pmu_inuse(1); > mtspr(SPRN_MMCRA, cpuhw->mmcr[2] & ~MMCRA_SAMPLE_ENABLE); > -- > 1.8.3.1 >
diff --git a/arch/powerpc/perf/core-book3s.c b/arch/powerpc/perf/core-book3s.c index 3086055..48bfdc9 100644 --- a/arch/powerpc/perf/core-book3s.c +++ b/arch/powerpc/perf/core-book3s.c @@ -1285,6 +1285,11 @@ static void power_pmu_enable(struct pmu *pmu) goto out; if (cpuhw->n_events == 0) { + /* + * Indicate PMU not in-use to Hypervisor. + * We end-up here via "ctx_sched_out()" from common code and + * "power_pmu_del()". + */ ppc_set_pmu_inuse(0); goto out; } @@ -1341,6 +1346,11 @@ static void power_pmu_enable(struct pmu *pmu) * Write the new configuration to MMCR* with the freeze * bit set and set the hardware events to their initial values. * Then unfreeze the events. + * ppc_set_pmu_inuse(1): "power_pmu_enable" will unset the + * "pmcregs_in_use" flag when a previous profiling/sampling session + * is completed and un-setting of flag will notify the Hypervisor to + * drop save/restore of PMU sprs. Now that PMU need to be enabled, first + * set the "pmcregs_in_use" flag in VPA. */ ppc_set_pmu_inuse(1); mtspr(SPRN_MMCRA, cpuhw->mmcr[2] & ~MMCRA_SAMPLE_ENABLE);