From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 AAFA447CC6A; Thu, 4 Jun 2026 14:07:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780582045; cv=none; b=K9xxjpkAbYWe1BYD8bvE59Jc5BhbhSccKpEy2plc9/0ISCqX7Mpzp8NIG8V58XLGkmZez7iW5HEWIfEC+ClV6xgTauh+Wyddi7A49UMnGa+YSdjoGQXV8MIDbs22GTFbEj8sN9LjWhXaGw+2jYnYzor2n7WHvJ53IJ7wpkwPMSk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780582045; c=relaxed/simple; bh=UIt8SFLjPgAFHAgsHxcs0u4I3gXlNxCBhbdA+WZyi+4=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=BkY6MOTBGsTYYj0013QPzVnWg8q5Ex5prxhM2MOzw64XedqN17LmHnlL+Yhvjg2k4PwSlzs/SisLb+RvPeVY57aCUaNbN4JIIVYyQzqksYz9NSlk/R6CK021Dpz19vZSLVWqRWhdECCZqVAqVl9be5r3uZ1ZtFIcYqFmu8OKniE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=HW/U0GSg; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="HW/U0GSg" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 67AB71F00893; Thu, 4 Jun 2026 14:07:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1780582043; bh=iLV5PSvnDbXsI12NPpxP91UyGJrfQLikYnozlkEwlZM=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=HW/U0GSgT/TQ53kIK9gysCoy1TmUG8jNtB4toZGIv65SSfaZOsD6WfApu0in7VIxu kF5sS2iVIUGc7uAZ+wTQ73wPJsmdcQS/eowwmRT4Gwy2lktebuKv59VfKv32QZe1v0 JcqfJNRtZu60BfYXi1FHVrJIw2BPOdPIh4/kp5oh5irtDnn/Tssbyhko1Js/5uoQ2F SJ8339O3PCH/tdYBh1yyexeqjOq3jnF2OXD5uo8FspGrD6Iqzb2j2ZbR7b2bwoXLsw 2dlGrWRtBPhZ/ffzsAgDSKiyVVtrAd1vcHidDyFyUxIiS7nCtymtgdi65ykixxyX6m VCIqWZDQPpRHw== Date: Thu, 4 Jun 2026 11:07:20 -0300 From: Arnaldo Carvalho de Melo To: Namhyung Kim 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: Re: [PATCH v2] perf lock contention: Allow 'mmap_lock' in -L/--lock-filter Message-ID: References: <20260505231136.691907-1-namhyung@kernel.org> Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260505231136.691907-1-namhyung@kernel.org> On Tue, May 05, 2026 at 04:11:35PM -0700, Namhyung Kim wrote: > 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 Hi, Did this fell thru the cracks? :-) - Arnaldo > 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