Messages in this thread Patch in this message | | | Date | Thu, 21 Mar 2024 16:58:17 -0300 | From | Arnaldo Carvalho de Melo <> | Subject | Re: [PATCH v4] perf lock contention: skip traceiter functions |
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Now lemme nitpick a bit, and I'll do it myself while processing the patch, some are from my days sending patches to Ingo and from his requests it become second nature, others I do to further clarify the text:
And here is the reason for top posting, the first request is about the subject line:
Subject: [PATCH v4] perf lock contention: skip traceiter functions
Becomes:
Subject: [PATCH v4] perf lock contention: Trim backtrace by skipping traceiter functions
Please make it so that after the component the one line summary starts with a capital letter and packs as much info as possible.
On Tue, Mar 19, 2024 at 02:36:26PM +0000, Anne Macedo wrote: > The perf lock contention program currently shows the caller of the locks
I try to make the sub (sub) command stand out by single quoting it:
The 'perf lock contention' program currently shows the caller of the locks
What follows is great, nice description, before/after.
Thanks, testing it now on x86_64 and aarch64, will apply it then.
- Arnaldo
> 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 > > changes since v3: > > - remove dummy value and assume machine->traceiter and machine->trace > have zero address > > changes since v2: > > - add dummy value to machine->traceiter and machine->trace to make > necessary checks, fixing possible null pointer access > > changes since v1: > > - consider trace_contention and __traceiter_contention functions as > optional (i.e. check if sym is null to avoid segfault) > > changes since v0: > > - skip trace_contention functions > - use sym->end instead of __traceiter_contention_end for text_end > > Signed-off-by: Anne Macedo <retpolanne@posteo.net> > --- > tools/perf/util/machine.c | 24 ++++++++++++++++++++++++ > tools/perf/util/machine.h | 2 +- > 2 files changed, 25 insertions(+), 1 deletion(-) > > diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c > index 527517db3182..5eb9044bc223 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 e28c787616fe..4312f6db6de0 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 */ > -- > 2.39.2 >
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