linux-kernel - Re: [PATCH v2 2/4] perf/x86: Fix data source decoding for Skylake

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Message-ID: <20170609164733.GB28361@tassilo.jf.intel.com>
Date:   Fri, 9 Jun 2017 09:47:33 -0700
From:   Andi Kleen <ak@...ux.intel.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Stephane Eranian <eranian@...gle.com>,
        Andi Kleen <andi@...stfloor.org>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Jiri Olsa <jolsa@...nel.org>,
        Sukadev Bhattiprolu <sukadev@...ux.vnet.ibm.com>,
        Madhavan Srinivasan <maddy@...ux.vnet.ibm.com>
Subject: Re: [PATCH v2 2/4] perf/x86: Fix data source decoding for Skylake

> > > So one thing we could do is add a mem_hops field and always set that,
> > > even for the old stuff. The old stuff will not know about that field and
> > > ignore the bits, but new stuff will then not need as many LVL bits.
> > >
> > That would be better than lvlx I think. I am guessing you're suggesting
> > an integer count here and not a bitmask. Right? 
> 
> Yah, 0 hops = local, etc..

This doesn't work on Skylake because it doesn't report the number of hops,
just remote or not.

Would need a wildcard entry, but that can as well be a separate bit.

That's what I did in the latest version of my patch.

-Andi