From: Anne Macedo Date: Tue, 19 Mar 2024 14:36:26 +0000 (+0000) Subject: perf lock contention: Trim backtrace by skipping traceiter functions X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=2a5049b75d22c971e73501784f10548c1d69c407;p=linux.git perf lock contention: Trim backtrace by skipping traceiter functions The 'perf lock contention' program currently shows the caller of the locks as __traceiter_contention_begin+0x??. This caller can be ignored, as it is from the traceiter itself. Instead, it should show the real callers for the locks. When fiddling with the --stack-skip parameter, the actual callers for the locks start to show up. However, just ignore the __traceiter_contention_begin and the __traceiter_contention_end symbols so the actual callers will show up. Before this patch is applied: sudo perf lock con -a -b -- sleep 3 contended total wait max wait avg wait type caller 8 2.33 s 2.28 s 291.18 ms rwlock:W __traceiter_contention_begin+0x44 4 2.33 s 2.28 s 582.35 ms rwlock:W __traceiter_contention_begin+0x44 7 140.30 ms 46.77 ms 20.04 ms rwlock:W __traceiter_contention_begin+0x44 2 63.35 ms 33.76 ms 31.68 ms mutex trace_contention_begin+0x84 2 46.74 ms 46.73 ms 23.37 ms rwlock:W __traceiter_contention_begin+0x44 1 13.54 us 13.54 us 13.54 us mutex trace_contention_begin+0x84 1 3.67 us 3.67 us 3.67 us rwsem:R __traceiter_contention_begin+0x44 Before this patch is applied - using --stack-skip 5 sudo perf lock con --stack-skip 5 -a -b -- sleep 3 contended total wait max wait avg wait type caller 2 2.24 s 2.24 s 1.12 s rwlock:W do_epoll_wait+0x5a0 4 1.65 s 824.21 ms 412.08 ms rwlock:W do_exit+0x338 2 824.35 ms 824.29 ms 412.17 ms spinlock get_signal+0x108 2 824.14 ms 824.14 ms 412.07 ms rwlock:W release_task+0x68 1 25.22 ms 25.22 ms 25.22 ms mutex cgroup_kn_lock_live+0x58 1 24.71 us 24.71 us 24.71 us spinlock do_exit+0x44 1 22.04 us 22.04 us 22.04 us rwsem:R lock_mm_and_find_vma+0xb0 After this patch is applied: sudo ./perf lock con -a -b -- sleep 3 contended total wait max wait avg wait type caller 4 4.13 s 2.07 s 1.03 s rwlock:W release_task+0x68 2 2.07 s 2.07 s 1.03 s rwlock:R mm_update_next_owner+0x50 2 2.07 s 2.07 s 1.03 s rwlock:W do_exit+0x338 1 41.56 ms 41.56 ms 41.56 ms mutex cgroup_kn_lock_live+0x58 2 36.12 us 18.83 us 18.06 us rwlock:W do_exit+0x338 Signed-off-by: Anne Macedo Acked-by: Namhyung Kim Tested-by: Arnaldo Carvalho de Melo Cc: Adrian Hunter Cc: Alexander Shishkin Cc: Ian Rogers Cc: Ingo Molnar Cc: Jiri Olsa Cc: Mark Rutland Cc: Peter Zijlstra Link: https://lore.kernel.org/r/20240319143629.3422590-1-retpolanne@posteo.net Signed-off-by: Arnaldo Carvalho de Melo --- diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c index 527517db31821..5eb9044bc223c 100644 --- a/tools/perf/util/machine.c +++ b/tools/perf/util/machine.c @@ -3266,6 +3266,17 @@ bool machine__is_lock_function(struct machine *machine, u64 addr) sym = machine__find_kernel_symbol_by_name(machine, "__lock_text_end", &kmap); machine->lock.text_end = map__unmap_ip(kmap, sym->start); + + sym = machine__find_kernel_symbol_by_name(machine, "__traceiter_contention_begin", &kmap); + if (sym) { + machine->traceiter.text_start = map__unmap_ip(kmap, sym->start); + machine->traceiter.text_end = map__unmap_ip(kmap, sym->end); + } + sym = machine__find_kernel_symbol_by_name(machine, "trace_contention_begin", &kmap); + if (sym) { + machine->trace.text_start = map__unmap_ip(kmap, sym->start); + machine->trace.text_end = map__unmap_ip(kmap, sym->end); + } } /* failed to get kernel symbols */ @@ -3280,5 +3291,18 @@ bool machine__is_lock_function(struct machine *machine, u64 addr) if (machine->lock.text_start <= addr && addr < machine->lock.text_end) return true; + /* traceiter functions currently don't have their own section + * but we consider them lock functions + */ + if (machine->traceiter.text_start != 0) { + if (machine->traceiter.text_start <= addr && addr < machine->traceiter.text_end) + return true; + } + + if (machine->trace.text_start != 0) { + if (machine->trace.text_start <= addr && addr < machine->trace.text_end) + return true; + } + return false; } diff --git a/tools/perf/util/machine.h b/tools/perf/util/machine.h index e28c787616fe4..4312f6db6de0a 100644 --- a/tools/perf/util/machine.h +++ b/tools/perf/util/machine.h @@ -49,7 +49,7 @@ struct machine { struct { u64 text_start; u64 text_end; - } sched, lock; + } sched, lock, traceiter, trace; pid_t *current_tid; size_t current_tid_sz; union { /* Tool specific area */