perf record: Lazy load kernel symbols

Commit 5b7ba82a75915e73 ("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
field to 'struct symbol_conf' to control the behavior and disable it for
'perf record' and 'perf inject'.

Reviewed-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ian Rogers <irogers@google.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Athira Jajeev <atrajeev@linux.vnet.ibm.com>
Cc: Changbin Du <changbin.du@huawei.com>
Cc: Colin Ian King <colin.i.king@gmail.com>
Cc: Dmitrii Dolgov <9erthalion6@gmail.com>
Cc: German Gomez <german.gomez@arm.com>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@arm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: K Prateek Nayak <kprateek.nayak@amd.com>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Li Dong <lidong@vivo.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Ming Wang <wangming01@loongson.cn>
Cc: Nick Terrell <terrelln@fb.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@amd.com>
Cc: Sandipan Das <sandipan.das@amd.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: Steinar H. Gunderson <sesse@google.com>
Cc: Vincent Whitchurch <vincent.whitchurch@axis.com>
Cc: Wenyu Liu <liuwenyu7@huawei.com>
Cc: Yang Jihong <yangjihong1@huawei.com>
Link: https://lore.kernel.org/r/20231102175735.2272696-3-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/builtin-inject.c b/tools/perf/builtin-inject.c
index c8cf2fdd9cff9637ebd97660321e858fa3aeb3e0..eb3ef5c24b66258c568dea02252975f1addb3924 100644 (file)
--- 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 dcf288a4fb9a9ad9281b2892272b4918c8f760e5..8ec818568662e49def499b6f5781b91d1048fb93 100644 (file)
--- 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 923c0fb1512226a60c7a01730c405ca15e6982c9..68f45e9e63b6e4f8fcdf6476dd0b2f9c3789dd3a 100644 (file)
--- 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 0b589570d1d095c1a20047cad399b7eb3a19a95a..2b2fb9e224b00876b0f2a44dd96c650affbad153 100644 (file)
--- 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,