linux-kernel - Re: [PATCH v2 05/11] perf expr: increase max other

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Date:   Wed, 6 May 2020 15:52:19 -0700
From:   Ian Rogers <irogers@...gle.com>
To:     Jiri Olsa <jolsa@...hat.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Kan Liang <kan.liang@...ux.intel.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Haiyan Song <haiyanx.song@...el.com>,
        Jin Yao <yao.jin@...ux.intel.com>,
        Song Liu <songliubraving@...com>,
        Ravi Bangoria <ravi.bangoria@...ux.ibm.com>,
        John Garry <john.garry@...wei.com>,
        Leo Yan <leo.yan@...aro.org>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Paul Clarke <pc@...ibm.com>,
        LKML <linux-kernel@...r.kernel.org>,
        linux-perf-users <linux-perf-users@...r.kernel.org>,
        Stephane Eranian <eranian@...gle.com>
Subject: Re: [PATCH v2 05/11] perf expr: increase max other

On Thu, Apr 23, 2020 at 7:23 AM Ian Rogers <irogers@...gle.com> wrote:
>
> On Thu, Apr 23, 2020 at 4:29 AM Jiri Olsa <jolsa@...hat.com> wrote:
> >
> > On Wed, Apr 22, 2020 at 03:04:24PM -0700, Ian Rogers wrote:
> > > Large metrics such as Branch_Misprediction_Cost_SMT on x86 broadwell
> > > need more space.
> > >
> > > Signed-off-by: Ian Rogers <irogers@...gle.com>
> > > ---
> > >  tools/perf/util/expr.h | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/tools/perf/util/expr.h b/tools/perf/util/expr.h
> > > index 0938ad166ece..4938bfc608b7 100644
> > > --- a/tools/perf/util/expr.h
> > > +++ b/tools/perf/util/expr.h
> > > @@ -2,7 +2,7 @@
> > >  #ifndef PARSE_CTX_H
> > >  #define PARSE_CTX_H 1
> > >
> > > -#define EXPR_MAX_OTHER 20
> > > +#define EXPR_MAX_OTHER 64
> > >  #define MAX_PARSE_ID EXPR_MAX_OTHER
> > >
> > >  struct expr_parse_id {
> > > --
> > > 2.26.2.303.gf8c07b1a785-goog
> > >
> >
> > ok, and we should probably start to think about what Andi suggested
> > in here: https://lore.kernel.org/lkml/20200224210308.GQ160988@tassilo.jf.intel.com/
>
> Agreed, a hash table would make sense. This was the smallest value
> that would let the test on x86 pass.

Fwiw, I have done this based on tools/lib/bpf/hashmap.h in CLs
following on from this patch set. I'm holding off sending so I can
rebase on acme's perf/next when the CLs acked by Jirka land:
https://lore.kernel.org/lkml/20200503221650.GA1916255@krava/
The libbpf dependency for a hashmap is counter intuitive, so maybe
there's something better to do there.

Thanks,
Ian

> Thanks,
> Ian
>
> > jirka
> >