Re: [PATCH] perf tools: Fix bug when recording SPE and non SPE events

[Leo Yan]

On Mon, Jan 13, 2020 at 10:17:51PM +0800, Leo Yan wrote:

[...]

> > > On Fri, Dec 20, 2019 at 11:05:25AM +0000, James Clark wrote:
> > > > This patch fixes an issue when non Arm SPE events are specified after an
> > > > Arm SPE event. In that case, perf will exit with an error code and not
> > > > produce a record file. This is because a loop index is used to store the
> > > > location of the relevant Arm SPE PMU, but if non SPE PMUs follow, that
> > > > index will be overwritten. Fix this issue by saving the PMU into a
> > > > variable instead of using the index, and also add an error message.
> > > > 
> > > > Before the fix:
> > > >      ./perf record -e arm_spe/ts_enable=1/ -e branch-misses ls; echo $?
> > > >      237
> > > > 
> > > > After the fix:
> > > >      ./perf record -e arm_spe/ts_enable=1/ -e branch-misses ls; echo $?
> > > >      ...
> > > >      0
> > > 
> > > Just bring up a question related with PMU event registration.  Let's
> > > see the DT binding in arch/arm64/boot/dts/arm/fvp-base-revc.dts:
> > > 
> > >           spe-pmu {
> > >                   compatible = "arm,statistical-profiling-extension-v1";
> > >                   interrupts = <GIC_PPI 5 IRQ_TYPE_LEVEL_HIGH>;
> > >           };
> > > 
> > > 
> > > Now SPE registers PMU event for every CPU; seem to me, though SPE is an
> > 
> > Do you mean "SPE PMU" here ? SPE is different from ETM, where the trace
> > data is micro-architecture dependent. And thus you cannot mix the trace
> > on different CPUs with different micro-archs.
> 
> Understood that SPE is micro-architecture dependent.

Maybe SPE is more general than we think :)

Since SPE is defined in ARMv8 architecture reference manual (ARM DDI
0487D.a); should SPE trace data format is unified and defined in Chapter
D9 "Statistical Profiling Extension Sample Record Specification"?

Thanks,
Leo