From nobody Fri Dec 19 07:15:53 2025 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 5D2FB1BB6A3; Thu, 29 Aug 2024 18:38:12 +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=1724956693; cv=none; b=bhnFXdXpk/059jwWFwn2vWnktnxJakwp5J4ZX0B5pdudR0NhtcYUwURiQv9NmInFuaD/dQhxjNXa31T4+bwE78vx4Qs2lg0jZueU5O0KBaoaMsWl3Uxu16hCm5ReXlB1b+kt4EeXvnQE61fyRjUHriTX+f+BZQ95EOKxWu7MGXs= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724956693; c=relaxed/simple; bh=Jv6KT2UGgAmwIKABURNXs74b2nTjkVTPbA6PDUOU5nQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=HLaI38mFbHsUnl2H0VzwfDs3gO3XLyloSOj2N0fG1GCnFaQp0SQW9gaCIaRNCzPtdyDB01fbYUtsBjBcJ8PDU9BSjsK27iqBsiblKxpPLuKMCDAniBDJDyaXYiV7xRpW9ZbeMfUhmjQrMnjHESUPUHOfqMcUrSkMxK0btdoafyQ= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=QnKvJP4g; 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="QnKvJP4g" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9D088C4CEC1; Thu, 29 Aug 2024 18:38:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1724956692; bh=Jv6KT2UGgAmwIKABURNXs74b2nTjkVTPbA6PDUOU5nQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=QnKvJP4gt4bTiecXgx46lcFCCvdZn8AOYqSJkL7xF8R8HkS8GsKEcPk0Eva0855YG z6Jd28llajhOMKffsONc8T9IUvkosxd4J69TVk0JuQ1I+7As0u/pRnq5gJbTBzi+U0 R+vHEuvTrFugTc+jD/Wry/pQGr/N3hzYPuduFcXn5moFYNmeuU6hIWbdktcP1O9/VZ F7cx3tZAKHOgEdAT3g0OrXtoqJQQh9HzqlFioNyVCh8AIFehHlJPvDtStRjhBgXE7c lDHpr11rkId9QOD5/3IAKTCWeB5V45KQ9Rohmooo4r2vZvd+1Qs2xuwpArgVVsnxUQ a6zswlYT80YaQ== From: Andrii Nakryiko To: linux-trace-kernel@vger.kernel.org, peterz@infradead.org, oleg@redhat.com Cc: rostedt@goodmis.org, mhiramat@kernel.org, bpf@vger.kernel.org, linux-kernel@vger.kernel.org, jolsa@kernel.org, paulmck@kernel.org, willy@infradead.org, surenb@google.com, akpm@linux-foundation.org, linux-mm@kvack.org, Andrii Nakryiko Subject: [PATCH v4 8/8] uprobes: switch to RCU Tasks Trace flavor for better performance Date: Thu, 29 Aug 2024 11:37:41 -0700 Message-ID: <20240829183741.3331213-9-andrii@kernel.org> X-Mailer: git-send-email 2.43.5 In-Reply-To: <20240829183741.3331213-1-andrii@kernel.org> References: <20240829183741.3331213-1-andrii@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-Transfer-Encoding: quoted-printable This patch switches uprobes SRCU usage to RCU Tasks Trace flavor, which is optimized for more lightweight and quick readers (at the expense of slower writers, which for uprobes is a fine tradeof) and has better performance and scalability with number of CPUs. Similarly to baseline vs SRCU, we've benchmarked SRCU-based implementation vs RCU Tasks Trace implementation. SRCU =3D=3D=3D=3D uprobe-nop ( 1 cpus): 3.276 =C2=B1 0.005M/s ( 3.276M/s/cpu) uprobe-nop ( 2 cpus): 4.125 =C2=B1 0.002M/s ( 2.063M/s/cpu) uprobe-nop ( 4 cpus): 7.713 =C2=B1 0.002M/s ( 1.928M/s/cpu) uprobe-nop ( 8 cpus): 8.097 =C2=B1 0.006M/s ( 1.012M/s/cpu) uprobe-nop (16 cpus): 6.501 =C2=B1 0.056M/s ( 0.406M/s/cpu) uprobe-nop (32 cpus): 4.398 =C2=B1 0.084M/s ( 0.137M/s/cpu) uprobe-nop (64 cpus): 6.452 =C2=B1 0.000M/s ( 0.101M/s/cpu) uretprobe-nop ( 1 cpus): 2.055 =C2=B1 0.001M/s ( 2.055M/s/cpu) uretprobe-nop ( 2 cpus): 2.677 =C2=B1 0.000M/s ( 1.339M/s/cpu) uretprobe-nop ( 4 cpus): 4.561 =C2=B1 0.003M/s ( 1.140M/s/cpu) uretprobe-nop ( 8 cpus): 5.291 =C2=B1 0.002M/s ( 0.661M/s/cpu) uretprobe-nop (16 cpus): 5.065 =C2=B1 0.019M/s ( 0.317M/s/cpu) uretprobe-nop (32 cpus): 3.622 =C2=B1 0.003M/s ( 0.113M/s/cpu) uretprobe-nop (64 cpus): 3.723 =C2=B1 0.002M/s ( 0.058M/s/cpu) RCU Tasks Trace =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D uprobe-nop ( 1 cpus): 3.396 =C2=B1 0.002M/s ( 3.396M/s/cpu) uprobe-nop ( 2 cpus): 4.271 =C2=B1 0.006M/s ( 2.135M/s/cpu) uprobe-nop ( 4 cpus): 8.499 =C2=B1 0.015M/s ( 2.125M/s/cpu) uprobe-nop ( 8 cpus): 10.355 =C2=B1 0.028M/s ( 1.294M/s/cpu) uprobe-nop (16 cpus): 7.615 =C2=B1 0.099M/s ( 0.476M/s/cpu) uprobe-nop (32 cpus): 4.430 =C2=B1 0.007M/s ( 0.138M/s/cpu) uprobe-nop (64 cpus): 6.887 =C2=B1 0.020M/s ( 0.108M/s/cpu) uretprobe-nop ( 1 cpus): 2.174 =C2=B1 0.001M/s ( 2.174M/s/cpu) uretprobe-nop ( 2 cpus): 2.853 =C2=B1 0.001M/s ( 1.426M/s/cpu) uretprobe-nop ( 4 cpus): 4.913 =C2=B1 0.002M/s ( 1.228M/s/cpu) uretprobe-nop ( 8 cpus): 5.883 =C2=B1 0.002M/s ( 0.735M/s/cpu) uretprobe-nop (16 cpus): 5.147 =C2=B1 0.001M/s ( 0.322M/s/cpu) uretprobe-nop (32 cpus): 3.738 =C2=B1 0.008M/s ( 0.117M/s/cpu) uretprobe-nop (64 cpus): 4.397 =C2=B1 0.002M/s ( 0.069M/s/cpu) Peak throughput for uprobes increases from 8 mln/s to 10.3 mln/s (+28%!), and for uretprobes from 5.3 mln/s to 5.8 mln/s (+11%), as we have more work to do on uretprobes side. Even single-thread (no contention) performance is slightly better: 3.276 mln/s to 3.396 mln/s (+3.5%) for uprobes, and 2.055 mln/s to 2.174 mln/s (+5.8%) for uretprobes. Signed-off-by: Andrii Nakryiko --- kernel/events/uprobes.c | 37 +++++++++++++++---------------------- 1 file changed, 15 insertions(+), 22 deletions(-) diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index 8a464cf38127..a5d39cec53d5 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -42,8 +42,6 @@ static struct rb_root uprobes_tree =3D RB_ROOT; static DEFINE_RWLOCK(uprobes_treelock); /* serialize rbtree access */ static seqcount_rwlock_t uprobes_seqcount =3D SEQCNT_RWLOCK_ZERO(uprobes_s= eqcount, &uprobes_treelock); =20 -DEFINE_STATIC_SRCU(uprobes_srcu); - #define UPROBES_HASH_SZ 13 /* serialize uprobe->pending_list */ static struct mutex uprobes_mmap_mutex[UPROBES_HASH_SZ]; @@ -652,7 +650,7 @@ static void put_uprobe(struct uprobe *uprobe) delayed_uprobe_remove(uprobe, NULL); mutex_unlock(&delayed_uprobe_lock); =20 - call_srcu(&uprobes_srcu, &uprobe->rcu, uprobe_free_rcu); + call_rcu_tasks_trace(&uprobe->rcu, uprobe_free_rcu); } =20 static __always_inline @@ -707,7 +705,7 @@ static struct uprobe *find_uprobe_rcu(struct inode *ino= de, loff_t offset) struct rb_node *node; unsigned int seq; =20 - lockdep_assert(srcu_read_lock_held(&uprobes_srcu)); + lockdep_assert(rcu_read_lock_trace_held()); =20 do { seq =3D read_seqcount_begin(&uprobes_seqcount); @@ -935,8 +933,7 @@ static bool filter_chain(struct uprobe *uprobe, struct = mm_struct *mm) bool ret =3D false; =20 down_read(&uprobe->consumer_rwsem); - list_for_each_entry_srcu(uc, &uprobe->consumers, cons_node, - srcu_read_lock_held(&uprobes_srcu)) { + list_for_each_entry_rcu(uc, &uprobe->consumers, cons_node, rcu_read_lock_= trace_held()) { ret =3D consumer_filter(uc, mm); if (ret) break; @@ -1157,7 +1154,7 @@ void uprobe_unregister_sync(void) * unlucky enough caller can free consumer's memory and cause * handler_chain() or handle_uretprobe_chain() to do an use-after-free. */ - synchronize_srcu(&uprobes_srcu); + synchronize_rcu_tasks_trace(); } EXPORT_SYMBOL_GPL(uprobe_unregister_sync); =20 @@ -1241,19 +1238,18 @@ EXPORT_SYMBOL_GPL(uprobe_register); int uprobe_apply(struct uprobe *uprobe, struct uprobe_consumer *uc, bool a= dd) { struct uprobe_consumer *con; - int ret =3D -ENOENT, srcu_idx; + int ret =3D -ENOENT; =20 down_write(&uprobe->register_rwsem); =20 - srcu_idx =3D srcu_read_lock(&uprobes_srcu); - list_for_each_entry_srcu(con, &uprobe->consumers, cons_node, - srcu_read_lock_held(&uprobes_srcu)) { + rcu_read_lock_trace(); + list_for_each_entry_rcu(con, &uprobe->consumers, cons_node, rcu_read_lock= _trace_held()) { if (con =3D=3D uc) { ret =3D register_for_each_vma(uprobe, add ? uc : NULL); break; } } - srcu_read_unlock(&uprobes_srcu, srcu_idx); + rcu_read_unlock_trace(); =20 up_write(&uprobe->register_rwsem); =20 @@ -2123,8 +2119,7 @@ static void handler_chain(struct uprobe *uprobe, stru= ct pt_regs *regs) =20 current->utask->auprobe =3D &uprobe->arch; =20 - list_for_each_entry_srcu(uc, &uprobe->consumers, cons_node, - srcu_read_lock_held(&uprobes_srcu)) { + list_for_each_entry_rcu(uc, &uprobe->consumers, cons_node, rcu_read_lock_= trace_held()) { int rc =3D 0; =20 if (uc->handler) { @@ -2162,15 +2157,13 @@ handle_uretprobe_chain(struct return_instance *ri, = struct pt_regs *regs) { struct uprobe *uprobe =3D ri->uprobe; struct uprobe_consumer *uc; - int srcu_idx; =20 - srcu_idx =3D srcu_read_lock(&uprobes_srcu); - list_for_each_entry_srcu(uc, &uprobe->consumers, cons_node, - srcu_read_lock_held(&uprobes_srcu)) { + rcu_read_lock_trace(); + list_for_each_entry_rcu(uc, &uprobe->consumers, cons_node, rcu_read_lock_= trace_held()) { if (uc->ret_handler) uc->ret_handler(uc, ri->func, regs); } - srcu_read_unlock(&uprobes_srcu, srcu_idx); + rcu_read_unlock_trace(); } =20 static struct return_instance *find_next_ret_chain(struct return_instance = *ri) @@ -2255,13 +2248,13 @@ static void handle_swbp(struct pt_regs *regs) { struct uprobe *uprobe; unsigned long bp_vaddr; - int is_swbp, srcu_idx; + int is_swbp; =20 bp_vaddr =3D uprobe_get_swbp_addr(regs); if (bp_vaddr =3D=3D uprobe_get_trampoline_vaddr()) return uprobe_handle_trampoline(regs); =20 - srcu_idx =3D srcu_read_lock(&uprobes_srcu); + rcu_read_lock_trace(); =20 uprobe =3D find_active_uprobe_rcu(bp_vaddr, &is_swbp); if (!uprobe) { @@ -2319,7 +2312,7 @@ static void handle_swbp(struct pt_regs *regs) =20 out: /* arch_uprobe_skip_sstep() succeeded, or restart if can't singlestep */ - srcu_read_unlock(&uprobes_srcu, srcu_idx); + rcu_read_unlock_trace(); } =20 /* --=20 2.43.5