Re: [PATCH V3 13/23] perf/x86/intel/lbr: Factor out intel_pmu_store_lbr

[Liang, Kan]

On 7/6/2020 6:25 AM, Peter Zijlstra wrote:
> On Fri, Jul 03, 2020 at 04:59:49PM -0400, Liang, Kan wrote:
> > On 7/3/2020 3:50 PM, Peter Zijlstra wrote:
>
> > > If I'm not mistaken, this correctly deals with LBR_FORMAT_INFO, so can't
> > > we also use the intel_pmu_arch_lbr_read() function for that case?
> >
> > But the intel_pmu_arch_lbr_read() doesn't have the optimization
> > (LBR_NO_INFO) for the LBR_FORMAT_INFO.
> > https://lkml.kernel.org/r/tip-b16a5b52eb90d92b597257778e51e1fdc6423e64@xxxxxxxxxxxxxx
> >
> > To apply the optimization, we need extra codes as below.
>
> Right, I saw that, but shouldn't we support that for anything with this
> format anyway? That is, it's weird and inconsistent to not support
> PERF_SAMPLE_BRANCH_NO_{CYCLES,FLAGS} for PEBS/ARCH-LBR output.

OK. I will support NO_{CYCLES,FLAGS} for PEBS/ARCH-LBR to make the 
output consistent.

> Arguably, we should even support NO_CYCLES for FORMAT_TIME. Yes it's
> daft, but that's what you get for adding the ABI.

I will add another patch to support NO_{CYCLES,FLAGS} for FORMAT_TIME.

The two patches will be on top of the "Support Architectural LBR" 
series. Can I send the two patches in a separate thread?


Thanks,
Kan