Messages in this thread | | | From | Namhyung Kim <> | Date | Sun, 5 Nov 2023 09:34:09 -0800 | Subject | Re: [PATCH v4 02/53] perf record: Lazy load kernel symbols |
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On Thu, Nov 2, 2023 at 10:58 AM Ian Rogers <irogers@google.com> wrote: > > Commit 5b7ba82a7591 ("perf symbols: Load kernel maps before using") > changed it so that loading a kernel dso would cause the symbols for > the dso to be eagerly loaded. For perf record this is overhead as the > symbols won't be used. Add a symbol_conf to control the behavior and > disable it for perf record and perf inject. > > Signed-off-by: Ian Rogers <irogers@google.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Thanks, Namhyung
> --- > tools/perf/builtin-inject.c | 6 ++++++ > tools/perf/builtin-record.c | 2 ++ > tools/perf/util/event.c | 4 ++-- > tools/perf/util/symbol_conf.h | 3 ++- > 4 files changed, 12 insertions(+), 3 deletions(-) > > diff --git a/tools/perf/builtin-inject.c b/tools/perf/builtin-inject.c > index c8cf2fdd9cff..eb3ef5c24b66 100644 > --- a/tools/perf/builtin-inject.c > +++ b/tools/perf/builtin-inject.c > @@ -2265,6 +2265,12 @@ int cmd_inject(int argc, const char **argv) > "perf inject [<options>]", > NULL > }; > + > + if (!inject.itrace_synth_opts.set) { > + /* Disable eager loading of kernel symbols that adds overhead to perf inject. */ > + symbol_conf.lazy_load_kernel_maps = true; > + } > + > #ifndef HAVE_JITDUMP > set_option_nobuild(options, 'j', "jit", "NO_LIBELF=1", true); > #endif > diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c > index dcf288a4fb9a..8ec818568662 100644 > --- a/tools/perf/builtin-record.c > +++ b/tools/perf/builtin-record.c > @@ -3989,6 +3989,8 @@ int cmd_record(int argc, const char **argv) > # undef set_nobuild > #endif > > + /* Disable eager loading of kernel symbols that adds overhead to perf record. */ > + symbol_conf.lazy_load_kernel_maps = true; > rec->opts.affinity = PERF_AFFINITY_SYS; > > rec->evlist = evlist__new(); > diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c > index 923c0fb15122..68f45e9e63b6 100644 > --- a/tools/perf/util/event.c > +++ b/tools/perf/util/event.c > @@ -617,13 +617,13 @@ struct map *thread__find_map(struct thread *thread, u8 cpumode, u64 addr, > if (cpumode == PERF_RECORD_MISC_KERNEL && perf_host) { > al->level = 'k'; > maps = machine__kernel_maps(machine); > - load_map = true; > + load_map = !symbol_conf.lazy_load_kernel_maps; > } else if (cpumode == PERF_RECORD_MISC_USER && perf_host) { > al->level = '.'; > } else if (cpumode == PERF_RECORD_MISC_GUEST_KERNEL && perf_guest) { > al->level = 'g'; > maps = machine__kernel_maps(machine); > - load_map = true; > + load_map = !symbol_conf.lazy_load_kernel_maps; > } else if (cpumode == PERF_RECORD_MISC_GUEST_USER && perf_guest) { > al->level = 'u'; > } else { > diff --git a/tools/perf/util/symbol_conf.h b/tools/perf/util/symbol_conf.h > index 0b589570d1d0..2b2fb9e224b0 100644 > --- a/tools/perf/util/symbol_conf.h > +++ b/tools/perf/util/symbol_conf.h > @@ -42,7 +42,8 @@ struct symbol_conf { > inline_name, > disable_add2line_warn, > buildid_mmap2, > - guest_code; > + guest_code, > + lazy_load_kernel_maps; > const char *vmlinux_name, > *kallsyms_name, > *source_prefix, > -- > 2.42.0.869.gea05f2083d-goog >
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