Messages in this thread | | | Date | Tue, 10 May 2022 10:28:44 +0100 | From | Will Deacon <> | Subject | Re: [PATCH V3] arm64: perf: Retain PMCR.X of PMCR_EL0 during reset |
| |
On Mon, May 09, 2022 at 10:58:50PM +0530, Srinivasarao Pathipati wrote: > Preserve the bit PMCR.X of PMCR_EL0 during PMU reset to export > PMU events. as it could be set before PMU initialization. > > Exporting events could result in additional power consumption > so making it configurable. > > Signed-off-by: Srinivasarao Pathipati <quic_c_spathi@quicinc.com> > --- > Changes since V2: > Done below changes as per Will's comments > - enabling pmcr_x now configurable with kernel parameters and > by default it is disabled. > > Changes since V1: > - Preserving only PMCR_X bit as per Robin Murphy's comment. > --- > Documentation/admin-guide/kernel-parameters.txt | 4 ++++ > arch/arm64/kernel/perf_event.c | 13 +++++++++++++ > 2 files changed, 17 insertions(+) > > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > index de3da15..cf3410e 100644 > --- a/Documentation/admin-guide/kernel-parameters.txt > +++ b/Documentation/admin-guide/kernel-parameters.txt > @@ -5150,6 +5150,10 @@ > Useful for devices that are detected asynchronously > (e.g. USB and MMC devices). > > + retain_pmcr_x > + [KNL] Retain export bit of PMCR_EL0 that is getting reset > + during pmu reset.
I think it would be better to build this as a sysctl so that it can be toggled at runtime as well.
Will
| |