[PATCH] perf mem2node: Improve warning if detected no memory nodes

[PATCH] perf mem2node: Improve warning if detected no memory nodes

[Leo Yan]

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@linaro.org>
---
 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

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

[Jiri Olsa]

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@linaro.org>

Acked-by: Jiri Olsa <jolsa@redhat.com>

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
> 

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

[Arnaldo Carvalho de Melo]

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@linaro.org>
> 
> Acked-by: Jiri Olsa <jolsa@redhat.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