linux-kernel - Re: [PATCH 1/4] perf annotate: Add a hashmap for symbol histogram

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Date: Tue, 27 Feb 2024 21:21:26 -0800
From: Namhyung Kim <namhyung@...nel.org>
To: Ian Rogers <irogers@...gle.com>
Cc: Arnaldo Carvalho de Melo <acme@...nel.org>, Jiri Olsa <jolsa@...nel.org>, 
	Adrian Hunter <adrian.hunter@...el.com>, Peter Zijlstra <peterz@...radead.org>, 
	Ingo Molnar <mingo@...nel.org>, LKML <linux-kernel@...r.kernel.org>, 
	linux-perf-users@...r.kernel.org, Andi Kleen <ak@...ux.intel.com>
Subject: Re: [PATCH 1/4] perf annotate: Add a hashmap for symbol histogram

On Tue, Feb 27, 2024 at 5:20 PM Ian Rogers <irogers@...gle.com> wrote:
>
> On Tue, Feb 27, 2024 at 4:52 PM Namhyung Kim <namhyung@...nel.org> wrote:
> >
> > Now symbol histogram uses an array to save per-offset sample counts.
> > But it wastes a lot of memory if the symbol has a few samples only.
> > Add a hashmap to save values only for actual samples.
> >
> > For now, it has duplicate histogram (one in the existing array and
> > another in the new hash map).  Once it can convert to use the hash
> > in all places, we can get rid of the array later.
> >
> > Signed-off-by: Namhyung Kim <namhyung@...nel.org>
> > ---
[SNIP]
> > diff --git a/tools/perf/util/annotate.h b/tools/perf/util/annotate.h
> > index 94435607c958..a2b0c8210740 100644
> > --- a/tools/perf/util/annotate.h
> > +++ b/tools/perf/util/annotate.h
> > @@ -12,6 +12,7 @@
> >  #include "symbol_conf.h"
> >  #include "mutex.h"
> >  #include "spark.h"
> > +#include "hashmap.h"
>
> nit: This could just be a forward reference to keep the number of
> header files down.

Sounds good.  Will fix in v2.

Thanks for your review!
Namhyung