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 A758A4086A; Mon, 4 May 2026 06:09:06 +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=1777874946; cv=none; b=bv0GQqbEzB6EZ740vP0aBtxIlmu7CMTABCwF3DgehYZ4vNs/e9ulTCPLgAc4gsmZ74u4iy9pk6bxvz6KskKQorF2D7gxc5qYb8kwFtLe1QZ0XJhO5/3fN5UNyTSejyb97zaEPLfVF5IMzBbiWOr6uWECqTNqnyzncNCCbTP1x70= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777874946; c=relaxed/simple; bh=hUGJZL3RZt2LIlxfbLcQWSchR9tyewETq9K0HRHhWQs=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=KrWPINYbJk/PIdduJbDGJNpU7agBkGprdRGUpthlOCtj9QTIjlFAZqxIV5imGUdqiN0OkhZX4mTaGxuEfvhjgLs1RW6/39dyhtW6zGkW9p3gXzfP90HXn7+kN2Q/dD+XfhebL54P9VPef6i5Qn5JfB6Q/fuoK/3Pt0DHuIwAliQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=XZ9Fzk6f; 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="XZ9Fzk6f" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9C472C2BCB8; Mon, 4 May 2026 06:09:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1777874946; bh=hUGJZL3RZt2LIlxfbLcQWSchR9tyewETq9K0HRHhWQs=; h=From:To:Cc:Subject:Date:From; b=XZ9Fzk6fFzBh054K5LtYDBqy/bTQepju9bK4wRbze7jfuwAypB0z8Cym8i0VtkfhZ vQRIf8chwcIsJEgpMUGeuWsb16syiMuxzH9Sx5W+DSOJXOXBI+lrcyPPDGFf/+AA33 QQFo9O0uzKPrRp1cygqJ1YO4hT5X4SdKcbzloAhsQM5kOuBcsX4NuVDOHy2hU+Nvet MxJbt+2FiYuRH5+cy4JkuFAdPNJwzrcHbdJLKE3aH/Up2/VW2bDK69azY0u9q6OYZ6 lyFsWezy4owdnViVhHADMUtcrE/pOpByONIb5KT+fRk7yjwKVbNc6e/dLs2ibu5pAV JXdmX+S7eGkfA== From: Namhyung Kim To: Arnaldo Carvalho de Melo , Ian Rogers , James Clark Cc: Jiri Olsa , Adrian Hunter , Peter Zijlstra , Ingo Molnar , LKML , linux-perf-users@vger.kernel.org, Chun-Tse Shao Subject: [PATCH] perf lock contention: Allow 'mmap_lock' in -L/--lock-filter Date: Sun, 3 May 2026 23:08:59 -0700 Message-ID: <20260504060859.84987-1-namhyung@kernel.org> X-Mailer: git-send-email 2.53.0 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 --- tools/perf/tests/shell/lock_contention.sh | 11 +++++++++++ tools/perf/util/bpf_lock_contention.c | 12 +++++++++++- tools/perf/util/bpf_skel/lock_contention.bpf.c | 11 +++++++++++ 3 files changed, 33 insertions(+), 1 deletion(-) 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..cd7ee5d1d1dd654e 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); @@ -264,7 +270,10 @@ int lock_contention_prepare(struct lock_contention *con) con->filters->addrs = addrs; } naddrs = con->filters->nr_addrs; - skel->rodata->has_addr = 1; + if (naddrs > 0) + skel->rodata->has_addr = 1; + else + naddrs = 1; } /* resolve lock name in delays */ @@ -298,6 +307,7 @@ 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..45ec2fb739842403 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; @@ -295,6 +298,14 @@ static inline int can_record(u64 *ctx) 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; + } + return 1; } -- 2.53.0