linux-kernel - Re: [PATCH v3 9/9] perf mem: Document event type 'ldst'

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Date:   Fri, 30 Oct 2020 09:49:23 +0800
From:   Leo Yan <leo.yan@...aro.org>
To:     Ian Rogers <irogers@...gle.com>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        John Garry <john.garry@...wei.com>,
        Will Deacon <will@...nel.org>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Kemeng Shi <shikemeng@...wei.com>,
        "Naveen N. Rao" <naveen.n.rao@...ux.vnet.ibm.com>,
        Al Grant <Al.Grant@....com>, James Clark <james.clark@....com>,
        Wei Li <liwei391@...wei.com>,
        André Przywara <andre.przywara@....com>,
        LKML <linux-kernel@...r.kernel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v3 9/9] perf mem: Document event type 'ldst'

Hi Ian,

On Thu, Oct 29, 2020 at 06:10:40PM -0700, Ian Rogers wrote:
> On Tue, Oct 27, 2020 at 11:39 PM Leo Yan <leo.yan@...aro.org> wrote:
> >
> > The event type 'ldst' is added for recording both load and store memory
> > operations, this patch documents for the new event type.
> >
> > Signed-off-by: Leo Yan <leo.yan@...aro.org>
> > ---
> >  tools/perf/Documentation/perf-mem.txt | 6 +++++-
> >  1 file changed, 5 insertions(+), 1 deletion(-)
> >
> > diff --git a/tools/perf/Documentation/perf-mem.txt b/tools/perf/Documentation/perf-mem.txt
> > index 199ea0f0a6c0..c50ef37dba72 100644
> > --- a/tools/perf/Documentation/perf-mem.txt
> > +++ b/tools/perf/Documentation/perf-mem.txt
> > @@ -38,7 +38,11 @@ OPTIONS
> >
> >  -t::
> >  --type=<type>::
> > -       Select the memory operation type: load or store (default: load,store)
> > +       Select the memory operation type: load, store, ldst (default: load,store).
> > +       The type 'ldst' means the single event can record both for load and store
> > +       operations; Intel and PowerPC support the types 'load' and 'store' but
> > +       'ldst' cannot be used; on Arm64, it uses Arm SPE as memory events and
> > +       user needs to specify one of these three types.
> 
> Naive question, could the type remain load,store for mem record and
> the tool internally change it to ldst for ARM SPE?

Good point.  I understand you are suggesting to avoid complex options
for usage, looked again at the code, my conclusion is it's feabile to
convert 'load,store' to Arm SPE's ldst type.

If find any block issue when I experiment this idea, will come back to
update it; otherwise, I will apply the suggestion in next spin.

Thanks for suggestion,
Leo