* [PATCH] perf: Ignore stripped vmlinux and fallback to kallsyms
@ 2014-09-08 22:59 Anton Blanchard
2014-09-12 6:33 ` Namhyung Kim
2014-09-19 5:22 ` [tip:perf/core] perf symbols: " tip-bot for Anton Blanchard
0 siblings, 2 replies; 3+ messages in thread
From: Anton Blanchard @ 2014-09-08 22:59 UTC (permalink / raw)
To: acme, a.p.zijlstra, paulus, mingo; +Cc: linux-kernel
If a vmlinux is stripped, perf will use it and ignore kallsyms. We
end up with useless profiles where everything maps to a few
runtime symbols:
63.39% swapper [kernel.kallsyms] [k] hcall_real_table
4.90% beam.smp [kernel.kallsyms] [k] hcall_real_table
4.44% beam.smp [kernel.kallsyms] [k] __sched_text_start
3.72% beam.smp [kernel.kallsyms] [k] __run_at_kexec
Detect this case and fallback to using kallsyms. This fixes the issue:
62.81% swapper [kernel.kallsyms] [k] snooze_loop
4.44% beam.smp [kernel.kallsyms] [k] __schedule
0.91% beam.smp [kernel.kallsyms] [k] _switch
0.73% beam.smp [kernel.kallsyms] [k] put_prev_entity
Signed-off-by: Anton Blanchard <anton@samba.org>
---
Index: b/tools/perf/util/symbol-elf.c
===================================================================
--- a/tools/perf/util/symbol-elf.c
+++ b/tools/perf/util/symbol-elf.c
@@ -712,6 +712,14 @@ int dso__load_sym(struct dso *dso, struc
symbols__delete(&dso->symbols[map->type]);
if (!syms_ss->symtab) {
+ /*
+ * If the vmlinux is stripped, fail so we will fall back
+ * to using kallsyms. The vmlinux runtime symbols aren't
+ * of much use.
+ */
+ if (dso->kernel)
+ goto out_elf_end;
+
syms_ss->symtab = syms_ss->dynsym;
syms_ss->symshdr = syms_ss->dynshdr;
}
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] perf: Ignore stripped vmlinux and fallback to kallsyms
2014-09-08 22:59 [PATCH] perf: Ignore stripped vmlinux and fallback to kallsyms Anton Blanchard
@ 2014-09-12 6:33 ` Namhyung Kim
2014-09-19 5:22 ` [tip:perf/core] perf symbols: " tip-bot for Anton Blanchard
1 sibling, 0 replies; 3+ messages in thread
From: Namhyung Kim @ 2014-09-12 6:33 UTC (permalink / raw)
To: Anton Blanchard; +Cc: acme, a.p.zijlstra, paulus, mingo, linux-kernel
Hi Anton,
On Tue, 9 Sep 2014 08:59:29 +1000, Anton Blanchard wrote:
> If a vmlinux is stripped, perf will use it and ignore kallsyms. We
> end up with useless profiles where everything maps to a few
> runtime symbols:
>
> 63.39% swapper [kernel.kallsyms] [k] hcall_real_table
> 4.90% beam.smp [kernel.kallsyms] [k] hcall_real_table
> 4.44% beam.smp [kernel.kallsyms] [k] __sched_text_start
> 3.72% beam.smp [kernel.kallsyms] [k] __run_at_kexec
>
> Detect this case and fallback to using kallsyms. This fixes the issue:
>
> 62.81% swapper [kernel.kallsyms] [k] snooze_loop
> 4.44% beam.smp [kernel.kallsyms] [k] __schedule
> 0.91% beam.smp [kernel.kallsyms] [k] _switch
> 0.73% beam.smp [kernel.kallsyms] [k] put_prev_entity
>
> Signed-off-by: Anton Blanchard <anton@samba.org>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Thanks,
Namhyung
> ---
>
> Index: b/tools/perf/util/symbol-elf.c
> ===================================================================
> --- a/tools/perf/util/symbol-elf.c
> +++ b/tools/perf/util/symbol-elf.c
> @@ -712,6 +712,14 @@ int dso__load_sym(struct dso *dso, struc
> symbols__delete(&dso->symbols[map->type]);
>
> if (!syms_ss->symtab) {
> + /*
> + * If the vmlinux is stripped, fail so we will fall back
> + * to using kallsyms. The vmlinux runtime symbols aren't
> + * of much use.
> + */
> + if (dso->kernel)
> + goto out_elf_end;
> +
> syms_ss->symtab = syms_ss->dynsym;
> syms_ss->symshdr = syms_ss->dynshdr;
> }
^ permalink raw reply [flat|nested] 3+ messages in thread* [tip:perf/core] perf symbols: Ignore stripped vmlinux and fallback to kallsyms
2014-09-08 22:59 [PATCH] perf: Ignore stripped vmlinux and fallback to kallsyms Anton Blanchard
2014-09-12 6:33 ` Namhyung Kim
@ 2014-09-19 5:22 ` tip-bot for Anton Blanchard
1 sibling, 0 replies; 3+ messages in thread
From: tip-bot for Anton Blanchard @ 2014-09-19 5:22 UTC (permalink / raw)
To: linux-tip-commits
Cc: acme, linux-kernel, paulus, mingo, anton, hpa, mingo,
a.p.zijlstra, namhyung, tglx
Commit-ID: d0b0d0406fe6743e734e1ba780155f8db5f713e6
Gitweb: http://git.kernel.org/tip/d0b0d0406fe6743e734e1ba780155f8db5f713e6
Author: Anton Blanchard <anton@samba.org>
AuthorDate: Tue, 9 Sep 2014 08:59:29 +1000
Committer: Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Wed, 17 Sep 2014 17:08:10 -0300
perf symbols: Ignore stripped vmlinux and fallback to kallsyms
If a vmlinux is stripped, perf will use it and ignore kallsyms. We
end up with useless profiles where everything maps to a few
runtime symbols:
63.39% swapper [kernel.kallsyms] [k] hcall_real_table
4.90% beam.smp [kernel.kallsyms] [k] hcall_real_table
4.44% beam.smp [kernel.kallsyms] [k] __sched_text_start
3.72% beam.smp [kernel.kallsyms] [k] __run_at_kexec
Detect this case and fallback to using kallsyms. This fixes the issue:
62.81% swapper [kernel.kallsyms] [k] snooze_loop
4.44% beam.smp [kernel.kallsyms] [k] __schedule
0.91% beam.smp [kernel.kallsyms] [k] _switch
0.73% beam.smp [kernel.kallsyms] [k] put_prev_entity
Signed-off-by: Anton Blanchard <anton@samba.org>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20140909085929.4a5a81f0@kryten
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/util/symbol-elf.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c
index 9c9b27f..2a92e10 100644
--- a/tools/perf/util/symbol-elf.c
+++ b/tools/perf/util/symbol-elf.c
@@ -717,6 +717,14 @@ int dso__load_sym(struct dso *dso, struct map *map,
symbols__delete(&dso->symbols[map->type]);
if (!syms_ss->symtab) {
+ /*
+ * If the vmlinux is stripped, fail so we will fall back
+ * to using kallsyms. The vmlinux runtime symbols aren't
+ * of much use.
+ */
+ if (dso->kernel)
+ goto out_elf_end;
+
syms_ss->symtab = syms_ss->dynsym;
syms_ss->symshdr = syms_ss->dynshdr;
}
^ permalink raw reply related [flat|nested] 3+ messages in thread
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2014-09-08 22:59 [PATCH] perf: Ignore stripped vmlinux and fallback to kallsyms Anton Blanchard
2014-09-12 6:33 ` Namhyung Kim
2014-09-19 5:22 ` [tip:perf/core] perf symbols: " tip-bot for Anton Blanchard
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