linux-kernel - Re: [PATCH] perf mem2node: Improve warning if detected no memory nodes

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Message-ID: <20201020120635.GC2294271@kernel.org>
Date:   Tue, 20 Oct 2020 09:06:35 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Jiri Olsa <jolsa@...hat.com>
Cc:     Leo Yan <leo.yan@...aro.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Ian Rogers <irogers@...gle.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] perf mem2node: Improve warning if detected no memory
 nodes

Em Tue, Oct 20, 2020 at 08:06:27AM +0200, Jiri Olsa escreveu:
> On Mon, Oct 19, 2020 at 08:36:13AM +0800, Leo Yan wrote:
> > Some archs (e.g. x86 and Arm64) don't enable the configuration
> > CONFIG_MEMORY_HOTPLUG by default, if this configuration is not enabled
> > when build the kernel image, the SysFS for memory nodes will be missed.
> > This results in perf tool has no chance to catpure the memory nodes
> > information, when perf tool reports the result and detects no memory
> > nodes, it outputs "assertion failed at util/mem2node.c:99".
> > 
> > The output log doesn't give out reason for the failure and users have no
> > clue for how to fix it.  This patch changes to use explicit way for
> > warning: it tells user that detected no memory nodes and suggests to
> > enable CONFIG_MEMORY_HOTPLUG for kernel building.
> > 
> > Signed-off-by: Leo Yan <leo.yan@...aro.org>
> 
> Acked-by: Jiri Olsa <jolsa@...hat.com>

Thanks, applied.

- Arnaldo

 
> thanks,
> jirka
> 
> > ---
> >  tools/perf/util/mem2node.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> > 
> > diff --git a/tools/perf/util/mem2node.c b/tools/perf/util/mem2node.c
> > index c84f5841c7ab..03a7d7b27737 100644
> > --- a/tools/perf/util/mem2node.c
> > +++ b/tools/perf/util/mem2node.c
> > @@ -96,7 +96,8 @@ int mem2node__init(struct mem2node *map, struct perf_env *env)
> >  
> >  	/* Cut unused entries, due to merging. */
> >  	tmp_entries = realloc(entries, sizeof(*entries) * j);
> > -	if (tmp_entries || WARN_ON_ONCE(j == 0))
> > +	if (tmp_entries ||
> > +	    WARN_ONCE(j == 0, "No memory nodes, is CONFIG_MEMORY_HOTPLUG enabled?\n"))
> >  		entries = tmp_entries;
> >  
> >  	for (i = 0; i < j; i++) {
> > -- 
> > 2.17.1
> > 
> 

-- 

- Arnaldo