2013-07-15 20:28:38

by Jason Wessel

Subject: [PATCH] perf: 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 <[email protected]>
---
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

2013-07-29 22:41:03

by David Ahern

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

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 <[email protected]>
> ---
> 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 <[email protected]>

2013-08-12 10:25:03

by tip-bot for Vasyl Gomonovych

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

Commit-ID: 8f76fcd902e3b3a7d6f6c695cc8bc053579eb179
Gitweb: http://git.kernel.org/tip/8f76fcd902e3b3a7d6f6c695cc8bc053579eb179
Author: Jason Wessel <[email protected]>
AuthorDate: Mon, 15 Jul 2013 15:27:53 -0500
Committer: Arnaldo Carvalho de Melo <[email protected]>
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 <[email protected]>
Acked-by: David Ahern <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
---
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);