From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 8E06F23D7DC; Tue, 5 May 2026 23:11:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778022697; cv=none; b=MymQP0cSWqRuXuBPF37f1GY4y/vrJzBzsp1edN3WcCqjrf7ho6tHgv9l991A7CLcK2OiDtClE2oI5o4RC/sb8KruC8AaK64UD5tVEnW1yK+u6c7lllx0WXkfQxHukGpL2Z9X9ukhJZGSyoz5VwmDhjyv+BBNBR8ZcPX0RaSnWEU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778022697; c=relaxed/simple; bh=0Bk5Tatr2mSLMqOEPOPN2GzjISZZ36/Iwr/OVM5M5oA=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=COMLuRaLnfjNuDcNvU41SsS7QR9fzhL1eI7RJ/VZl43bn/yoTnXVaEnmI8wlWnzs7WOrEgT1WxUe8EXD1DK6bfwyeZbDtjMgu3ELUvusJti6qujO3E7HSwmskwzhVxvcLdRB9ITfvUqDhFLWeQ/wbBTZ4Iz2ZSs4Oi9JD7LmYhE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=HokjvtOy; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="HokjvtOy" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AD2AEC2BCB4; Tue, 5 May 2026 23:11:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1778022697; bh=0Bk5Tatr2mSLMqOEPOPN2GzjISZZ36/Iwr/OVM5M5oA=; h=From:To:Cc:Subject:Date:From; b=HokjvtOySbXojkNcLiNPd3yyAFKtZn0YgRwr/EqgqzBSoTQJG+mmoMOf1G1L4OdgQ UEXy0vq56bWrrZTqV8mOsSPtjIVKEWrHmMZdnAUg/lh0QiQNbZcu7VUMVUbGy0AGWe R00/WGMg5sxaND82luaFgzc6Dihi7AuTkPWHyUkfRMHmxOwwOjmK0mFUFLvzUgNPpD UZZ4MMFRjbLFVHHyRN6gIlhWjnZfNqaQhRKzBYrj25WLP2o9DZzFvwA4m55gSxEX7S Qd6LGQM68geeTXL154PL5Du8vUUEyXgoiMKBFUmDQ5ZEVzZSNFAqIIp75vrgNs8clO eOJ1HkwZU6/TA== From: Namhyung Kim To: Arnaldo Carvalho de Melo Cc: Ian Rogers , Jiri Olsa , Adrian Hunter , James Clark , Peter Zijlstra , Ingo Molnar , LKML , linux-perf-users@vger.kernel.org, Chun-Tse Shao , Suchit Karunakaran Subject: [PATCH v2] perf lock contention: Allow 'mmap_lock' in -L/--lock-filter Date: Tue, 5 May 2026 16:11:35 -0700 Message-ID: <20260505231136.691907-1-namhyung@kernel.org> X-Mailer: git-send-email 2.54.0.545.g6539524ca2-goog Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The -L/--lock-filter option is to specify target locks by name or address. It's basically for global locks where name or address is known and fixed. But 'mmap_lock' is a per-process lock so it cannot be used for the -L option. $ sudo perf lock con -ab -L mmap_lock ignore unknown symbol: mmap_lock libbpf: map 'addr_filter': failed to create: -EINVAL libbpf: failed to load BPF skeleton 'lock_contention_bpf': -EINVAL Failed to load lock-contention BPF skeleton lock contention BPF setup failed However, it's still a common source of contention especially in a large process so we want to use it for the -L/--lock-filter option. As there is check_lock_type() to check mmap_lock at runtime, let's used it to filter mmap_locks as a special case. Of course, this only works with -b/--use-bpf option. $ sudo perf lock con -b -L mmap_lock -- perf bench mem mmap -f demand -t 2 # Running 'mem/mmap' benchmark: # function 'demand' (Demand loaded mmap()) # Copying 1MB bytes ... 2.679184 GB/sec/thread ( +- 1.78% ) contended total wait max wait avg wait type caller 1 15.22 us 15.22 us 15.22 us rwsem:W __vm_munmap+0x7e 1 7.72 us 7.72 us 7.72 us rwsem:R lock_mm_and_find_vma+0x97 Signed-off-by: Namhyung Kim --- v2) * handle a bad lock name for -L option (Sashiko) * handle mmap_lock and other lock together (Sashiko) tools/perf/tests/shell/lock_contention.sh | 11 +++++++++ tools/perf/util/bpf_lock_contention.c | 9 +++++++- .../perf/util/bpf_skel/lock_contention.bpf.c | 23 +++++++++++++++++-- 3 files changed, 40 insertions(+), 3 deletions(-) diff --git a/tools/perf/tests/shell/lock_contention.sh b/tools/perf/tests/shell/lock_contention.sh index 6dd90519f45cec1d..52e8b9db9fbd8844 100755 --- a/tools/perf/tests/shell/lock_contention.sh +++ b/tools/perf/tests/shell/lock_contention.sh @@ -208,6 +208,17 @@ test_lock_filter() err=1 exit fi + + perf lock con -b -L mmap_lock -q -- perf bench mem mmap -t 2 -l 10 > /dev/null 2> ${result} + + # find out the type of mmap_lock + test_lock_filter_type=$(head -1 "${result}" | awk '{ print $8 }' | sed -e 's/:.*//') + + if [ "$(grep -c -v "${test_lock_filter_type}" "${result}")" != "0" ]; then + echo "[Fail] BPF result should not have non-${test_lock_filter_type} locks:" "$(cat "${result}")" + err=1 + exit + fi } test_stack_filter() diff --git a/tools/perf/util/bpf_lock_contention.c b/tools/perf/util/bpf_lock_contention.c index cbd7435579feaf8e..eb8e29b8064b7348 100644 --- a/tools/perf/util/bpf_lock_contention.c +++ b/tools/perf/util/bpf_lock_contention.c @@ -186,6 +186,7 @@ int lock_contention_prepare(struct lock_contention *con) int ncpus = 1, ntasks = 1, ntypes = 1, naddrs = 1, ncgrps = 1, nslabs = 1; struct evlist *evlist = con->evlist; struct target *target = con->target; + bool has_mmap_lock = false; /* make sure it loads the kernel map before lookup */ map__load(machine__kernel_map(con->machine)); @@ -244,6 +245,11 @@ int lock_contention_prepare(struct lock_contention *con) unsigned long *addrs; for (i = 0; i < con->filters->nr_syms; i++) { + if (!strcmp(con->filters->syms[i], "mmap_lock")) { + has_mmap_lock = true; + continue; + } + sym = machine__find_kernel_symbol_by_name(con->machine, con->filters->syms[i], &kmap); @@ -263,7 +269,7 @@ int lock_contention_prepare(struct lock_contention *con) addrs[con->filters->nr_addrs++] = map__unmap_ip(kmap, sym->start); con->filters->addrs = addrs; } - naddrs = con->filters->nr_addrs; + naddrs = con->filters->nr_addrs ?: has_mmap_lock; skel->rodata->has_addr = 1; } @@ -298,6 +304,7 @@ int lock_contention_prepare(struct lock_contention *con) skel->rodata->aggr_mode = con->aggr_mode; skel->rodata->needs_callstack = con->save_callstack; skel->rodata->lock_owner = con->owner; + skel->rodata->has_mmap_lock = has_mmap_lock; if (con->aggr_mode == LOCK_AGGR_CGROUP || con->filters->nr_cgrps) { if (cgroup_is_v2("perf_event")) diff --git a/tools/perf/util/bpf_skel/lock_contention.bpf.c b/tools/perf/util/bpf_skel/lock_contention.bpf.c index 96e7d853b9edf3b5..8b1aa64deb6e4141 100644 --- a/tools/perf/util/bpf_skel/lock_contention.bpf.c +++ b/tools/perf/util/bpf_skel/lock_contention.bpf.c @@ -184,6 +184,7 @@ const volatile int has_type; const volatile int has_addr; const volatile int has_cgroup; const volatile int has_slab; +const volatile int has_mmap_lock; const volatile int needs_callstack; const volatile int stack_skip; const volatile int lock_owner; @@ -214,6 +215,8 @@ int data_map_full; struct task_struct *bpf_task_from_pid(s32 pid) __ksym __weak; void bpf_task_release(struct task_struct *p) __ksym __weak; +static inline __u32 check_lock_type(__u64 lock, __u32 flags); + static inline __u64 get_current_cgroup_id(void) { struct task_struct *task; @@ -239,6 +242,8 @@ static inline __u64 get_current_cgroup_id(void) static inline int can_record(u64 *ctx) { + bool is_addr_ok = false; + if (has_cpu) { __u32 cpu = bpf_get_smp_processor_id(); __u8 *ok; @@ -271,8 +276,10 @@ static inline int can_record(u64 *ctx) __u64 addr = ctx[0]; ok = bpf_map_lookup_elem(&addr_filter, &addr); - if (!ok && !has_slab) + if (!ok && !has_slab && !has_mmap_lock) return 0; + + is_addr_ok = !!ok; } if (has_cgroup) { @@ -284,6 +291,10 @@ static inline int can_record(u64 *ctx) return 0; } + if (is_addr_ok) + return 1; + + /* slab and mmap_lock are part of the addr_filter */ if (has_slab && bpf_get_kmem_cache) { __u8 *ok; __u64 addr = ctx[0]; @@ -291,7 +302,15 @@ static inline int can_record(u64 *ctx) kmem_cache_addr = (long)bpf_get_kmem_cache(addr); ok = bpf_map_lookup_elem(&slab_filter, &kmem_cache_addr); - if (!ok) + if (!ok && !has_mmap_lock) + return 0; + } + + if (has_mmap_lock) { + __u64 lock = ctx[0]; + __u32 flag = ctx[1]; + + if (check_lock_type(lock, flag) != LCD_F_MMAP_LOCK) return 0; } -- 2.54.0.545.g6539524ca2-goog