linux-kernel - Re: [PATCH 2/6] perf/x86: Fix data source decoding for Skylake

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Date:   Tue, 6 Jun 2017 18:21:08 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Andi Kleen <andi@...stfloor.org>
Cc:     acme@...nel.org, linux-kernel@...r.kernel.org, jolsa@...nel.org,
        Andi Kleen <ak@...ux.intel.com>,
        Stephane Eranian <eranian@...gle.com>
Subject: Re: [PATCH 2/6] perf/x86: Fix data source decoding for Skylake

On Tue, Jun 06, 2017 at 06:51:20AM -0700, Andi Kleen wrote:
> > Not too happy about that..
> > 
> >   P(LVLX, L4) | P(LVLX, REMOTE)
> > 
> > reads like something that should be PERF_MEM_LVL_REM_CCE1 or something
> 
> CCE1? You mean L4?

#define PERF_MEM_LVL_REM_CCE1   0x400 /* Remote Cache (1 hop) */

It says 'cache' which is irrespective of level.

> The two bits seem cleaner to me than enumerating all cases.  But ok.

I tend to agree that a separate remote,distance,type fields would have
been nicer, but we seem to be stuck with this REM_* crud..

> > This new generic 'REMOTE' has too much overlap with the existing things.
> 
> So you want a REM_NA ?

Not sure... What's the point of a REM_NA vs regular NA ? "'something'
happened 'not here'" vs "'something' happened".

I hope Stephane has better ideas, he seems to be the one that introduced
this in the first place.