Messages in this thread Patch in this message | | | Date | Fri, 26 Jan 2018 15:48:30 +0900 | From | Namhyung Kim <> | Subject | Re: [PATCH 2/2] perf tools: Skip read of kernel maps once it failed |
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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/tip-ld2kp994rhz6i341igt8f98y@git.kernel.org > Signed-off-by: Jiri Olsa <jolsa@kernel.org> > --- > 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 >
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