From patchwork Wed Jul 31 21:42:56 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Andrii Nakryiko X-Patchwork-Id: 13749256 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 68AAE16EB5E; Wed, 31 Jul 2024 21:43:27 +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=1722462207; cv=none; b=nDnH6QyI6oafQAH2CWjp5/BuU7RaxZCMsvtgx2KCzTB0THQLpG69JuxgRztBc2Tbft9I9qKVAeJ9ksPMMSYUyE0tXqlABnj7wSe2A1asFNDSsfMUDngH70fTh3wBiz5D3MuZvcLFvhuigE1WbmwJDA+zQp0f5e/X6k7pYWNtWt4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722462207; c=relaxed/simple; bh=3Up2x3Nsu059ngkFWBfnfc1N6oPXYNPJasw54szZ3LA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=sVRS8vqxl6pcEqe3KvW/gedXLg8IxKpyA5Oj+wD9648gXuRRCHQQVD9Wd45cdN7cvHbLIuU5IBW+UXKx7hhRvC4e8Eifxh8fDRRXxdQcyuopdqXZHT/nfPlHuAiRE7lgdJcy15GpMJN/piXCVwJaoAc/QQtETupx3VqLxFSF66c= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=KpSCwLNN; 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="KpSCwLNN" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C3242C116B1; Wed, 31 Jul 2024 21:43:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1722462207; bh=3Up2x3Nsu059ngkFWBfnfc1N6oPXYNPJasw54szZ3LA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=KpSCwLNNZ0CvRYwYHiEcmBcn8uMYIhjR3l1zqeq7eXDrWtL2NtpOg7ub0BO5tVqK2 qY3u74GVN/fOlNbBRcQ+C1IY00Ng0cFIvgitr1kS5PeQYtLuRpLuiQAYu/nWhvNayh LCUBJQACUfeD6z5HbJc2oEZrR45hPnUqLcfggBmeiybCYyme3UKImL6N6nw4oM2RcS noMXmC8ZiZh9pG7Z4kGo1A0cd9/5mJrtTGqVfxCHX6s+GQsloQy4FaWgpKqfa9/Mup hZ1vErQQdcODQNCisZzoV7vrVtYeddIOsLuK1kJhXZsc7L653EdR+Zo8nNjVUtrKGG ziLn6VgFekMhQ== From: Andrii Nakryiko To: linux-trace-kernel@vger.kernel.org, peterz@infradead.org, oleg@redhat.com, rostedt@goodmis.org, mhiramat@kernel.org Cc: bpf@vger.kernel.org, linux-kernel@vger.kernel.org, jolsa@kernel.org, paulmck@kernel.org, Andrii Nakryiko Subject: [PATCH 8/8] uprobes: switch to RCU Tasks Trace flavor for better performance Date: Wed, 31 Jul 2024 14:42:56 -0700 Message-ID: <20240731214256.3588718-9-andrii@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240731214256.3588718-1-andrii@kernel.org> References: <20240731214256.3588718-1-andrii@kernel.org> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 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 ==== uprobe-nop ( 1 cpus): 3.276 ± 0.005M/s ( 3.276M/s/cpu) uprobe-nop ( 2 cpus): 4.125 ± 0.002M/s ( 2.063M/s/cpu) uprobe-nop ( 4 cpus): 7.713 ± 0.002M/s ( 1.928M/s/cpu) uprobe-nop ( 8 cpus): 8.097 ± 0.006M/s ( 1.012M/s/cpu) uprobe-nop (16 cpus): 6.501 ± 0.056M/s ( 0.406M/s/cpu) uprobe-nop (32 cpus): 4.398 ± 0.084M/s ( 0.137M/s/cpu) uprobe-nop (64 cpus): 6.452 ± 0.000M/s ( 0.101M/s/cpu) uretprobe-nop ( 1 cpus): 2.055 ± 0.001M/s ( 2.055M/s/cpu) uretprobe-nop ( 2 cpus): 2.677 ± 0.000M/s ( 1.339M/s/cpu) uretprobe-nop ( 4 cpus): 4.561 ± 0.003M/s ( 1.140M/s/cpu) uretprobe-nop ( 8 cpus): 5.291 ± 0.002M/s ( 0.661M/s/cpu) uretprobe-nop (16 cpus): 5.065 ± 0.019M/s ( 0.317M/s/cpu) uretprobe-nop (32 cpus): 3.622 ± 0.003M/s ( 0.113M/s/cpu) uretprobe-nop (64 cpus): 3.723 ± 0.002M/s ( 0.058M/s/cpu) RCU Tasks Trace =============== uprobe-nop ( 1 cpus): 3.396 ± 0.002M/s ( 3.396M/s/cpu) uprobe-nop ( 2 cpus): 4.271 ± 0.006M/s ( 2.135M/s/cpu) uprobe-nop ( 4 cpus): 8.499 ± 0.015M/s ( 2.125M/s/cpu) uprobe-nop ( 8 cpus): 10.355 ± 0.028M/s ( 1.294M/s/cpu) uprobe-nop (16 cpus): 7.615 ± 0.099M/s ( 0.476M/s/cpu) uprobe-nop (32 cpus): 4.430 ± 0.007M/s ( 0.138M/s/cpu) uprobe-nop (64 cpus): 6.887 ± 0.020M/s ( 0.108M/s/cpu) uretprobe-nop ( 1 cpus): 2.174 ± 0.001M/s ( 2.174M/s/cpu) uretprobe-nop ( 2 cpus): 2.853 ± 0.001M/s ( 1.426M/s/cpu) uretprobe-nop ( 4 cpus): 4.913 ± 0.002M/s ( 1.228M/s/cpu) uretprobe-nop ( 8 cpus): 5.883 ± 0.002M/s ( 0.735M/s/cpu) uretprobe-nop (16 cpus): 5.147 ± 0.001M/s ( 0.322M/s/cpu) uretprobe-nop (32 cpus): 3.738 ± 0.008M/s ( 0.117M/s/cpu) uretprobe-nop (64 cpus): 4.397 ± 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 | 40 +++++++++++++++++----------------------- 1 file changed, 17 insertions(+), 23 deletions(-) diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index d03962cc96de..ef915f87d27f 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -42,8 +42,6 @@ static struct rb_root uprobes_tree = RB_ROOT; static DEFINE_RWLOCK(uprobes_treelock); /* serialize rbtree access */ static seqcount_rwlock_t uprobes_seqcount = SEQCNT_RWLOCK_ZERO(uprobes_seqcount, &uprobes_treelock); -DEFINE_STATIC_SRCU(uprobes_srcu); - #define UPROBES_HASH_SZ 13 /* serialize uprobe->pending_list */ static struct mutex uprobes_mmap_mutex[UPROBES_HASH_SZ]; @@ -647,7 +645,7 @@ static void put_uprobe(struct uprobe *uprobe) delayed_uprobe_remove(uprobe, NULL); mutex_unlock(&delayed_uprobe_lock); - call_srcu(&uprobes_srcu, &uprobe->rcu, uprobe_free_rcu); + call_rcu_tasks_trace(&uprobe->rcu, uprobe_free_rcu); } static __always_inline @@ -702,7 +700,7 @@ static struct uprobe *find_uprobe_rcu(struct inode *inode, loff_t offset) struct rb_node *node; unsigned int seq; - lockdep_assert(srcu_read_lock_held(&uprobes_srcu)); + lockdep_assert(rcu_read_lock_trace_held()); do { seq = read_seqcount_begin(&uprobes_seqcount); @@ -919,8 +917,7 @@ static bool filter_chain(struct uprobe *uprobe, struct mm_struct *mm) bool ret = false; 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 = consumer_filter(uc, mm); if (ret) break; @@ -1132,7 +1129,7 @@ EXPORT_SYMBOL_GPL(uprobe_unregister_nosync); void uprobe_unregister_sync(void) { - synchronize_srcu(&uprobes_srcu); + synchronize_rcu_tasks_trace(); } EXPORT_SYMBOL_GPL(uprobe_unregister_sync); @@ -1216,19 +1213,18 @@ EXPORT_SYMBOL_GPL(uprobe_register); int uprobe_apply(struct uprobe *uprobe, struct uprobe_consumer *uc, bool add) { struct uprobe_consumer *con; - int ret = -ENOENT, srcu_idx; + int ret = -ENOENT; down_write(&uprobe->register_rwsem); - srcu_idx = 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 == uc) { ret = register_for_each_vma(uprobe, add ? uc : NULL); break; } } - srcu_read_unlock(&uprobes_srcu, srcu_idx); + rcu_read_unlock_trace(); up_write(&uprobe->register_rwsem); @@ -2105,8 +2101,7 @@ static void handler_chain(struct uprobe *uprobe, struct pt_regs *regs) bool need_prep = false; /* prepare return uprobe, when needed */ bool has_consumers = false; - 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 = 0; if (uc->handler) { @@ -2143,15 +2138,14 @@ handle_uretprobe_chain(struct return_instance *ri, struct pt_regs *regs) { struct uprobe *uprobe = ri->uprobe; struct uprobe_consumer *uc; - int srcu_idx; - srcu_idx = 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(); } static struct return_instance *find_next_ret_chain(struct return_instance *ri) @@ -2236,13 +2230,13 @@ static void handle_swbp(struct pt_regs *regs) { struct uprobe *uprobe; unsigned long bp_vaddr; - int is_swbp, srcu_idx; + int is_swbp; bp_vaddr = uprobe_get_swbp_addr(regs); if (bp_vaddr == uprobe_get_trampoline_vaddr()) return uprobe_handle_trampoline(regs); - srcu_idx = srcu_read_lock(&uprobes_srcu); + rcu_read_lock_trace(); uprobe = find_active_uprobe_rcu(bp_vaddr, &is_swbp); if (!uprobe) { @@ -2260,7 +2254,7 @@ static void handle_swbp(struct pt_regs *regs) */ instruction_pointer_set(regs, bp_vaddr); } - srcu_read_unlock(&uprobes_srcu, srcu_idx); + rcu_read_unlock_trace(); return; } @@ -2301,7 +2295,7 @@ static void handle_swbp(struct pt_regs *regs) out: /* arch_uprobe_skip_sstep() succeeded, or restart if can't singlestep */ - srcu_read_unlock(&uprobes_srcu, srcu_idx); + rcu_read_unlock_trace(); } /*