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 971441DFD90; Mon, 18 Nov 2024 18:35:45 +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=1731954945; cv=none; b=e3+A+y7tjY0Nj9mEMDCAXgvkTLiRVJBzVoHk55d/17MsELQkZgmrZg/90YLQozVpAxyS6qn2+8djKAr6QVlGyykR3rQSzWW/atW2JOW/xO6j4fGL1Yaw8FAHpuaHAEm9Qivr7ih/I+xuhr9O/QvZyNy1QuJbOxwDf/O8UqqRN+g= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1731954945; c=relaxed/simple; bh=J10+qtzOq0u5Tyf00UAPhHE+lr2XkJlRQct4kFIls4U=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=XUekMKLVQykyHaod/wb5TW4TdqirjSwrLhgtuEo16Zvt4XtaqLKTx+3cJjqEbu0R94xYdgWzI5dE5CCY48/E6+ROm/ciLSb79xQGROQBkvfaAIGw2hUCRBD7hZtuvCiqwNHuJLw/As3i3HHlH+qzo37pNBCbgQPPwSkDqFBYlPM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=sgY+VPmO; 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="sgY+VPmO" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 943C9C4CECC; Mon, 18 Nov 2024 18:35:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1731954945; bh=J10+qtzOq0u5Tyf00UAPhHE+lr2XkJlRQct4kFIls4U=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=sgY+VPmOa8tNjb0F9PWaYywwwXt5OjGKyvLq3p1vNR+RIwqN+MEN963e603ESgfnB p56tvxHPcl2IaF+Vvyi5GS+Kdql5vq7GZk06tU3V80+Sge+ANKS5qaC9fQwYX6cLO2 wtvNsLTjrBngMEPs6I1kW32Ati5ReYQBc/DAJpfUeIH6xwoM9dyG8ZZVR12/3ewzEA U/6SKJuJiT7KUK84W1739uHftj4r3dTb8Smp/FkQ9ks3IdaXDwmvEn4fRbMmhbqCXX UQ1zNXb8PJTjUOOq5YD7B2+CK9eMllTPU6z77JgmfxCeKkaLBPNVzDsBvZT7m2pzX1 Y651wyUCQn97g== Date: Mon, 18 Nov 2024 10:35:43 -0800 From: Namhyung Kim To: Ian Rogers Cc: Arnaldo Carvalho de Melo , Kan Liang , Jiri Olsa , Adrian Hunter , Peter Zijlstra , Ingo Molnar , LKML , linux-perf-users@vger.kernel.org, Andrii Nakryiko , Song Liu , bpf@vger.kernel.org, Stephane Eranian , Vlastimil Babka , Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com>, Kees Cook Subject: Re: [PATCH v2 0/4] perf lock contention: Symbolize locks using slab cache names Message-ID: References: <20241108061500.2698340-1-namhyung@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Mon, Nov 11, 2024 at 11:46:37AM -0800, Ian Rogers wrote: > On Thu, Nov 7, 2024 at 10:15 PM Namhyung Kim wrote: > > > > Hello, > > > > This is to support symbolization of dynamic locks using slab > > allocator's metadata. The kernel support is in the bpf-next tree now. > > > > It provides the new "kmem_cache" BPF iterator and "bpf_get_kmem_cache" > > kfunc to get the information from an address. The feature detection is > > done using BTF type info and it won't have any effect on old kernels. > > > > v2 changes) > > > > * don't use libbpf_get_error() (Andrii) > > > > v1) https://lore.kernel.org/linux-perf-users/20241105172635.2463800-1-namhyung@kernel.org > > > > With this change, it can show locks in a slab object like below. I > > added "&" sign to distinguish them from global locks. > > I know the & is intentional but I worry it could later complicate > parsing of filters. Perhaps @ is a viable alternative. Other than > that: > > Acked-by: Ian Rogers Thanks for the review! I don't think it clashes with BPF sample filters which works on sample data generated from a perf_event. Technically this command doesn't use perf_event and just attaches the BPF program to tracepoint directly. Also sample filters don't use '&' symbol in the syntax as of now. :) Thanks, Namhyung > > > # perf lock con -abl sleep 1 > > contended total wait max wait avg wait address symbol > > > > 2 1.95 us 1.77 us 975 ns ffff9d5e852d3498 &task_struct (mutex) > > 1 1.18 us 1.18 us 1.18 us ffff9d5e852d3538 &task_struct (mutex) > > 4 1.12 us 354 ns 279 ns ffff9d5e841ca800 &kmalloc-cg-512 (mutex) > > 2 859 ns 617 ns 429 ns ffffffffa41c3620 delayed_uprobe_lock (mutex) > > 3 691 ns 388 ns 230 ns ffffffffa41c0940 pack_mutex (mutex) > > 3 421 ns 164 ns 140 ns ffffffffa3a8b3a0 text_mutex (mutex) > > 1 409 ns 409 ns 409 ns ffffffffa41b4cf8 tracepoint_srcu_srcu_usage (mutex) > > 2 362 ns 239 ns 181 ns ffffffffa41cf840 pcpu_alloc_mutex (mutex) > > 1 220 ns 220 ns 220 ns ffff9d5e82b534d8 &signal_cache (mutex) > > 1 215 ns 215 ns 215 ns ffffffffa41b4c28 tracepoint_srcu_srcu_usage (mutex) > > > > The first two were from "task_struct" slab cache. It happened to > > match with the type name of object but there's no guarantee. We need > > to add type info to slab cache to resolve the lock inside the object. > > Anyway, the third one has no dedicated slab cache and was allocated by > > kmalloc. > > > > Those slab objects can be used to filter specific locks using -L or > > --lock-filter option. (It needs quotes to avoid special handling in > > the shell). > > > > # perf lock con -ab -L '&task_struct' sleep 1 > > contended total wait max wait avg wait type caller > > > > 1 25.10 us 25.10 us 25.10 us mutex perf_event_exit_task+0x39 > > 1 21.60 us 21.60 us 21.60 us mutex futex_exit_release+0x21 > > 1 5.56 us 5.56 us 5.56 us mutex futex_exec_release+0x21 > > > > The code is available at 'perf/lock-slab-v2' branch in my tree > > > > git://git.kernel.org/pub/scm/linux/kernel/git/namhyung/linux-perf.git > > > > Thanks, > > Namhyung > > > > > > Namhyung Kim (4): > > perf lock contention: Add and use LCB_F_TYPE_MASK > > perf lock contention: Run BPF slab cache iterator > > perf lock contention: Resolve slab object name using BPF > > perf lock contention: Handle slab objects in -L/--lock-filter option > > > > tools/perf/builtin-lock.c | 39 ++++- > > tools/perf/util/bpf_lock_contention.c | 140 +++++++++++++++++- > > .../perf/util/bpf_skel/lock_contention.bpf.c | 70 ++++++++- > > tools/perf/util/bpf_skel/lock_data.h | 15 +- > > tools/perf/util/bpf_skel/vmlinux/vmlinux.h | 8 + > > tools/perf/util/lock-contention.h | 2 + > > 6 files changed, 267 insertions(+), 7 deletions(-) > > > > -- > > 2.47.0.277.g8800431eea-goog > >