Re: [PATCH V4 07/14] perf/x86/intel: Support hardware TopDown metrics

[Peter Zijlstra]

On Mon, Sep 30, 2019 at 12:17:57PM -0400, Liang, Kan wrote:
> 
> 
> On 9/30/2019 10:53 AM, Peter Zijlstra wrote:
> > 
> > After that, I think we can simply do something like:
> > 
> > icl_update_topdown_event(..)
> 
> We should call this function in x86_pmu_commit_txn()?

Nah, we could use that TXN_READ stuff, but I don't think we have to. We
just raely on having done all ->read() callbacks before doing
perf_event_count().

> > {
> > 	int idx = event->hwc.idx;
> > 
> > 	if (is_metric_idx(idx))
> > 		return;
> > 
> > 	// must be FIXED_SLOTS
> 
> The FIXED_SLOTS may not be in the group.

Argh.. can we mandate that it is? that is, if you want a metric thing,
you have to have a slots counter first?