From nobody Sun Feb 8 18:09:41 2026 Received: from mout01.posteo.de (mout01.posteo.de [185.67.36.65]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 96F331B7E5 for ; Fri, 15 Mar 2024 11:19:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.67.36.65 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1710501569; cv=none; b=tn6NV75NXJf5pY7ynG6McIbHN0rwXFZP00kOk7BrWo7pg55VZFRiuRcqc1/L3aaHZJgTo/vxp+rGTjwmr6hBpgRWzeCoTPHxmllYHBHp2fPI3abTqYYy/vZFGtLKnU6P/40kizAnjvhYK24mR2cQN33w13VacRlHEvBQW/CAxkQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1710501569; c=relaxed/simple; bh=pwl/ZGxNVzBYAh4anc3xOfMFeMbKqlbpzCtmLz2rWjU=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=fSt0rbKW0DZODISqHe5TWdt/IQxs9u/yj/dtwdMJczIwO9krOjFFz007nvqHF9W2wtWs3L8qHkdX3uS4iQ5xu4++yDPY3nhblITyUF0nf1V4MpsI9hmRlC1lkvfdOZkI709nMGHeC5N7Kuudz9Jzyz5JEj41yULsMHb9l9KJZEQ= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=posteo.net; spf=pass smtp.mailfrom=posteo.net; dkim=pass (2048-bit key) header.d=posteo.net header.i=@posteo.net header.b=j3MXVxle; arc=none smtp.client-ip=185.67.36.65 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=posteo.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=posteo.net Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=posteo.net header.i=@posteo.net header.b="j3MXVxle" Received: from submission (posteo.de [185.67.36.169]) by mout01.posteo.de (Postfix) with ESMTPS id 369A124002A for ; Fri, 15 Mar 2024 12:19:20 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=posteo.net; s=2017; t=1710501560; bh=pwl/ZGxNVzBYAh4anc3xOfMFeMbKqlbpzCtmLz2rWjU=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version: Content-Transfer-Encoding:From; b=j3MXVxle8/VivUQGcbrd0C2IuZofA4ZpoKYFOtwZpGVpYtPLtieMLS8L2LDYYq5DC XyFslOxjPQuDiP2EcNLlfKNoie1nBs4F2eR+AQxZ01Llg5Yon5kkg1EKDF0GgqgGgA vQJQeGqNl9kSpPh62bQTydQghmBdytHyRUw4cNQ7GY3cURmfgvGANU1GTaVoLtDgKp oWK5tkac0uGzUDWpOvPC9/w7qQJe/oEqLThs+bhNko6hOz8vX6Gv4knn1Av62godRf zBaWxue+CGC7CdZZa2ozwuccYSseHBkdWtC84t3he88mmpW9Xk95pcimx5ODu8Q5Mf X8f3fhxxpX1KA== Received: from customer (localhost [127.0.0.1]) by submission (posteo.de) with ESMTPSA id 4Tx1wf1wbBz6tw2; Fri, 15 Mar 2024 12:19:13 +0100 (CET) From: Anne Macedo To: Arnaldo Carvalho de Melo , Namhyung Kim Cc: Anne Macedo , Peter Zijlstra , Ingo Molnar , Mark Rutland , Alexander Shishkin , Jiri Olsa , Ian Rogers , Adrian Hunter , linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v3] perf lock contention: skip traceiter functions Date: Fri, 15 Mar 2024 11:19:05 +0000 Message-Id: <20240315111907.1434909-1-retpolanne@posteo.net> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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 __traceite= r_contention_begin+0x44 4 2.33 s 2.28 s 582.35 ms rwlock:W __traceite= r_contention_begin+0x44 7 140.30 ms 46.77 ms 20.04 ms rwlock:W __traceite= r_contention_begin+0x44 2 63.35 ms 33.76 ms 31.68 ms mutex trace_cont= ention_begin+0x84 2 46.74 ms 46.73 ms 23.37 ms rwlock:W __traceite= r_contention_begin+0x44 1 13.54 us 13.54 us 13.54 us mutex trace_cont= ention_begin+0x84 1 3.67 us 3.67 us 3.67 us rwsem:R __traceite= r_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_w= ait+0x5a0 4 1.65 s 824.21 ms 412.08 ms rwlock:W do_exit+0x= 338 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_ta= sk+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+0x= 44 1 22.04 us 22.04 us 22.04 us rwsem:R lock_mm_an= d_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_ta= sk+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+0x= 338 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+0x= 338 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 --- tools/perf/util/machine.c | 29 +++++++++++++++++++++++++++++ tools/perf/util/machine.h | 2 +- 2 files changed, 30 insertions(+), 1 deletion(-) diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c index 527517db3182..373a3b852f72 100644 --- a/tools/perf/util/machine.c +++ b/tools/perf/util/machine.c @@ -3266,6 +3266,22 @@ bool machine__is_lock_function(struct machine *machi= ne, u64 addr) =20 sym =3D machine__find_kernel_symbol_by_name(machine, "__lock_text_end", = &kmap); machine->lock.text_end =3D map__unmap_ip(kmap, sym->start); + + sym =3D machine__find_kernel_symbol_by_name(machine, "__traceiter_conten= tion_begin", &kmap); + if (sym) { + machine->traceiter.text_start =3D map__unmap_ip(kmap, sym->start); + machine->traceiter.text_end =3D map__unmap_ip(kmap, sym->end); + } else { + machine->traceiter.text_start =3D 1; + } + + sym =3D machine__find_kernel_symbol_by_name(machine, "trace_contention_b= egin", &kmap); + if (sym) { + machine->trace.text_start =3D map__unmap_ip(kmap, sym->start); + machine->trace.text_end =3D map__unmap_ip(kmap, sym->end); + } else { + machine->trace.text_start =3D 1; + } } =20 /* failed to get kernel symbols */ @@ -3280,5 +3296,18 @@ bool machine__is_lock_function(struct machine *machi= ne, u64 addr) if (machine->lock.text_start <=3D addr && addr < machine->lock.text_end) return true; =20 + /* traceiter functions currently don't have their own section + * but we consider them lock functions + */ + if (machine->traceiter.text_start !=3D 1) { + if (machine->traceiter.text_start <=3D addr && addr < machine->traceiter= .text_end) + return true; + } + + if (machine->trace.text_start !=3D 1) { + if (machine->trace.text_start <=3D addr && addr < machine->trace.text_en= d) + 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 */ --=20 2.39.2