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 <an...@samba.org>
Acked-by: Namhyung Kim <namhy...@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;
> }
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