[PATCH] perf: Do not require /lib/modules/* on a guest

[PATCH] perf: Do not require /lib/modules/* on a guest

[Jason Wessel]

For some types of work loads and special guest environments, you might
have a kernel that has no kernel modules.  The perf kvm record tool
fails instantiate vmlinux maps when the kernel modules directory
cannot be opened, even though the kallsyms has been properly
processed.  This leads to a perf kvm report that has no guest symbols
resolved.

This patch changes the failure to locate kernel modules to be
non-fatal.

Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
---
 tools/perf/util/machine.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index b2ecad6..eb9ebd6 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -808,7 +808,10 @@ static int machine__create_modules(struct machine *machine)
 	free(line);
 	fclose(file);
 
-	return machine__set_modules_path(machine);
+	if (machine__set_modules_path(machine) < 0) {
+		pr_debug("Problems setting modules path maps, continuing anyway...\n");
+	}
+	return 0;
 
 out_delete_line:
 	free(line);
-- 
1.7.9.5

Re: [PATCH] perf: Do not require /lib/modules/* on a guest

[David Ahern]

On 7/15/13 2:27 PM, Jason Wessel wrote:
> For some types of work loads and special guest environments, you might
> have a kernel that has no kernel modules.  The perf kvm record tool
> fails instantiate vmlinux maps when the kernel modules directory
> cannot be opened, even though the kallsyms has been properly
> processed.  This leads to a perf kvm report that has no guest symbols
> resolved.

Theoretically, use of modules is an option:

     if (symbol_conf.use_modules && machine__create_modules(machine) < 0) {
...
     }

But, the use_modules option was flipped from false to true by b32d133a 
back in 2009. And the lack of complaints suggests this ominous warning 
in perf-report, diff and annotate is moot:

     OPT_BOOLEAN('m', "modules", &symbol_conf.use_modules,
             "load module symbols - WARNING: use only with -k and LIVE 
kernel"),

>
> This patch changes the failure to locate kernel modules to be
> non-fatal.
>
> Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
> ---
>   tools/perf/util/machine.c |    5 ++++-
>   1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
> index b2ecad6..eb9ebd6 100644
> --- a/tools/perf/util/machine.c
> +++ b/tools/perf/util/machine.c
> @@ -808,7 +808,10 @@ static int machine__create_modules(struct machine *machine)
>   	free(line);
>   	fclose(file);
>
> -	return machine__set_modules_path(machine);
> +	if (machine__set_modules_path(machine) < 0) {
> +		pr_debug("Problems setting modules path maps, continuing anyway...\n");
> +	}
> +	return 0;
>
>   out_delete_line:
>   	free(line);

Acked-by: David Ahern <dsahern@gmail.com>

[tip:perf/core] perf machine: Do not require /lib/modules/ * on a guest

[tip-bot for Jason Wessel]

Commit-ID:  8f76fcd902e3b3a7d6f6c695cc8bc053579eb179
Gitweb:     http://git.kernel.org/tip/8f76fcd902e3b3a7d6f6c695cc8bc053579eb179
Author:     Jason Wessel <jason.wessel@windriver.com>
AuthorDate: Mon, 15 Jul 2013 15:27:53 -0500
Committer:  Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Wed, 7 Aug 2013 17:35:41 -0300

perf machine: Do not require /lib/modules/* on a guest

For some types of work loads and special guest environments, you might
have a kernel that has no kernel modules.  The perf kvm record tool
fails instantiate vmlinux maps when the kernel modules directory cannot
be opened, even though the kallsyms has been properly processed.  This
leads to a perf kvm report that has no guest symbols resolved.

This patch changes the failure to locate kernel modules to be non-fatal.

Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Acked-by: David Ahern <dsahern@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1373920073-4874-1-git-send-email-jason.wessel@windriver.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/util/machine.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index ef3b49c..6fcc358 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -806,7 +806,10 @@ static int machine__create_modules(struct machine *machine)
 	free(line);
 	fclose(file);
 
-	return machine__set_modules_path(machine);
+	if (machine__set_modules_path(machine) < 0) {
+		pr_debug("Problems setting modules path maps, continuing anyway...\n");
+	}
+	return 0;
 
 out_delete_line:
 	free(line);