linux-kernel - Re: [PATCH] perf hist browser: change print format from lu to llu to fit u64 type

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Message-ID: <20141126075721.GC26946@krava.brq.redhat.com>
Date:	Wed, 26 Nov 2014 08:57:21 +0100
From:	Jiri Olsa <jolsa@...hat.com>
To:	Tom Huynh <tom.huynh@...escale.com>, mingo@...hat.com,
	acme@...nel.org, namhyung@...nel.org, jolsa@...nel.org,
	a.p.zijlstra@...llo.nl, paulus@...ba.org,
	kim.phillips@...escale.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] perf hist browser: change print format from lu to llu to
 fit u64 type

On Tue, Nov 25, 2014 at 03:51:30PM -0800, Matt Mullins wrote:
> On Tue, Nov 18, 2014 at 05:00:27PM -0600, Tom Huynh wrote:
> > nr_events in tools/perf/ui/browsers/hists.c is of type u64, thus it should
> > be printed as %llu instead of %lu. The print format %lu causes perf report
> > to show 0 event count when running with 32-bit userspace without 
> > redirection. This patch fixes that problem.
> > 
> > Signed-off-by: Tom Huynh <tom.huynh@...escale.com>
> > ---
> >  tools/perf/ui/browsers/hists.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/tools/perf/ui/browsers/hists.c b/tools/perf/ui/browsers/hists.c
> > index cfb976b..49b2471 100644
> > --- a/tools/perf/ui/browsers/hists.c
> > +++ b/tools/perf/ui/browsers/hists.c
> > @@ -1254,7 +1254,7 @@ static int hists__browser_title(struct hists *hists,
> >  
> >  	nr_samples = convert_unit(nr_samples, &unit);
> >  	printed = scnprintf(bf, size,
> > -			   "Samples: %lu%c of event '%s', Event count (approx.): %lu",
> > +			   "Samples: %lu%c of event '%s', Event count (approx.): %llu",
> >  			   nr_samples, unit, ev_name, nr_events);
> 
> If I enable __attribute__((format(printf, ...))) on scnprintf, on a 64-bit
> build this gives me:
> 
> ui/browsers/hists.c: In function ‘hists__browser_title’:
> ui/browsers/hists.c:1258:7: error: format ‘%llu’ expects argument of type ‘long long unsigned int’, but argument 7 has type ‘u64’ [-Werror=format=]
>        nr_samples, unit, ev_name, nr_events);
>        ^
> 
> I would usually suggest using the PRIu64 macro which should(TM) evaluate to the
> right string constant for the platform, but that appears to be a C99 thing.
> I'm not sure if that's kosher in tools/perf, but it does seem to build for me
> (on Fedora 20).

[jolsa@...va linux-perf]$ grep -rI PRIu64 tools/perf/ | wc -l
97

yep, it's kosher enough ;-)

jirka
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