On Fri, Jan 19, 2018 at 05:11:03PM +0100, Jiri Olsa wrote:
> Current perf report is real slow on newer kernels,
> with following commit:
> c0f3ea158939 ("stop using '%pK' for /proc/kallsyms pointer values")
>
> which prevent pointers in /proc/kallsyms, in case
> kernel.perf_event_paranoid=2.
>
> That makes perf to fail in finding kernel map details,
> and keep parsing it again for every kernel sample.
>
> Adding and setting a new machine::vmlinux_maps_failed
> flag after first failed parsing attempt and using it
> to prevent new pointless parsing.
Hmm.. is it because it's called from machine__resolve() right?
/*
* Have we already created the kernel maps for this machine?
*
* This should have happened earlier, when we processed the kernel MMAP
* events, but for older perf.data files there was no such thing, so do
* it now.
*/
It seems that it's only to be compatible with ancient versions.
Do we still need it? I guess they are recorded many years ago (with
the ancient version) so using addresses of current kernel is just
meaningless. If one still uses the ancient version, [s]he really
needs to update it.
Thanks,
Namhyung
>
> TODO We might want to add some perf report warning
> about that.
>
> Link: http://lkml.kernel.org/n/[email protected]
> Signed-off-by: Jiri Olsa <[email protected]>
> ---
> tools/perf/util/machine.c | 6 ++++--
> tools/perf/util/machine.h | 1 +
> 2 files changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
> index b05a67464c03..5e9648817077 100644
> --- a/tools/perf/util/machine.c
> +++ b/tools/perf/util/machine.c
> @@ -1222,13 +1222,15 @@ int machine__create_kernel_maps(struct machine
> *machine)
> u64 addr = 0;
> int ret;
>
> - if (kernel == NULL)
> + if (kernel == NULL || machine->vmlinux_maps_failed)
> return -1;
>
> ret = __machine__create_kernel_maps(machine, kernel);
> dso__put(kernel);
> - if (ret < 0)
> + if (ret < 0) {
> + machine->vmlinux_maps_failed = true;
> return -1;
> + }
>
> if (symbol_conf.use_modules && machine__create_modules(machine) < 0) {
> if (machine__is_host(machine))
> diff --git a/tools/perf/util/machine.h b/tools/perf/util/machine.h
> index 5ce860b64c74..edcb007333cb 100644
> --- a/tools/perf/util/machine.h
> +++ b/tools/perf/util/machine.h
> @@ -42,6 +42,7 @@ struct machine {
> u16 id_hdr_size;
> bool comm_exec;
> bool kptr_restrict_warned;
> + bool vmlinux_maps_failed;
> char *root_dir;
> struct threads threads[THREADS__TABLE_SIZE];
> struct vdso_info *vdso_info;
> --
> 2.13.6
>
