From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 26895 invoked by alias); 14 May 2014 08:21:34 -0000 Mailing-List: contact systemtap-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Post: List-Help: , Sender: systemtap-owner@sourceware.org Received: (qmail 26825 invoked by uid 89); 14 May 2014 08:21:34 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.9 required=5.0 tests=AWL,BAYES_00,RCVD_IN_DNSWL_LOW,SPF_PASS autolearn=ham version=3.3.2 X-HELO: mail4.hitachi.co.jp Received: from mail4.hitachi.co.jp (HELO mail4.hitachi.co.jp) (133.145.228.5) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Wed, 14 May 2014 08:21:33 +0000 Received: from mlsv2.hitachi.co.jp (unknown [133.144.234.166]) by mail4.hitachi.co.jp (Postfix) with ESMTP id 3EC4033CCA; Wed, 14 May 2014 17:21:31 +0900 (JST) Received: from mfilter03.hitachi.co.jp by mlsv2.hitachi.co.jp (8.13.1/8.13.1) id s4E8LVZl018042; Wed, 14 May 2014 17:21:31 +0900 Received: from vshuts01.hitachi.co.jp (vshuts01.hitachi.co.jp [10.201.6.83]) by mfilter03.hitachi.co.jp (Switch-3.3.4/Switch-3.3.4) with ESMTP id s4E8LTZL014417; Wed, 14 May 2014 17:21:30 +0900 Received: from gxml20a.ad.clb.hitachi.co.jp (unknown [158.213.157.160]) by vshuts01.hitachi.co.jp (Postfix) with ESMTP id 59DDD2F0120; Wed, 14 May 2014 17:21:29 +0900 (JST) Received: from ltc230.yrl.intra.hitachi.co.jp by gxml20a.ad.clb.hitachi.co.jp (Switch-3.1.10/Switch-3.1.9) id 64E80LSUR0000FC90; Wed, 14 May 2014 17:21:28 +0900 Subject: [PATCH -tip v11 7/7] ftrace: Introduce FTRACE_OPS_FL_SELF_FILTER for ftrace-kprobe From: Masami Hiramatsu To: linux-kernel@vger.kernel.org, Ingo Molnar Cc: Andi Kleen , Ananth N Mavinakayanahalli , Sandeepa Prabhu , Frederic Weisbecker , x86@kernel.org, Steven Rostedt , fche@redhat.com, mingo@redhat.com, systemtap@sourceware.org, "H. Peter Anvin" , Thomas Gleixner Date: Wed, 14 May 2014 08:21:00 -0000 Message-ID: <20140514082123.5791.52424.stgit@ltc230.yrl.intra.hitachi.co.jp> In-Reply-To: <20140514082034.5791.38607.stgit@ltc230.yrl.intra.hitachi.co.jp> References: <20140514082034.5791.38607.stgit@ltc230.yrl.intra.hitachi.co.jp> User-Agent: StGit/0.17-dirty MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-IsSubscribed: yes X-SW-Source: 2014-q2/txt/msg00152.txt.bz2 Since the kprobes itself owns a hash table to get a kprobe data structure corresponding to the given ip address, there is no need to test ftrace hash in ftrace side. To achive better performance on ftrace-based kprobe, FTRACE_OPS_FL_SELF_FILTER flag to ftrace_ops which means that ftrace skips testing its own hash table. Without this patch, ftrace_lookup_ip() is biggest cycles consumer when 20,000 kprobes are enabled. ---- Samples: 1K of event 'cycles', Event count (approx.): 340068894 + 20.77% [k] ftrace_lookup_ip + 8.33% [k] kprobe_trace_func + 4.83% [k] get_kprobe_cached ---- With this patch, ftrace_lookup_ip() vanished from the cycles consumer list (of course, there is no caller on hotpath anymore :)) ---- Samples: 1K of event 'cycles', Event count (approx.): 186861492 + 9.95% [k] kprobe_trace_func + 6.00% [k] kprobe_ftrace_handler + 5.53% [k] get_kprobe_cached ---- Changes from v10: - Update comment of the flag according to Steven's comment. Changes from v7: - Re-evaluate the performance improvement. Signed-off-by: Masami Hiramatsu Cc: Steven Rostedt Cc: Frederic Weisbecker Cc: Ingo Molnar --- include/linux/ftrace.h | 3 +++ kernel/kprobes.c | 2 +- kernel/trace/ftrace.c | 3 ++- 3 files changed, 6 insertions(+), 2 deletions(-) diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index ae9504b..5653001 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -93,6 +93,8 @@ typedef void (*ftrace_func_t)(unsigned long ip, unsigned long parent_ip, * INITIALIZED - The ftrace_ops has already been initialized (first use time * register_ftrace_function() is called, it will initialized the ops) * DELETED - The ops are being deleted, do not let them be registered again. + * SELF_FILTER - The ftrace_ops function has its own ip filter and does not + * need to rely on the ftrace internal ip filtering. */ enum { FTRACE_OPS_FL_ENABLED = 1 << 0, @@ -105,6 +107,7 @@ enum { FTRACE_OPS_FL_STUB = 1 << 7, FTRACE_OPS_FL_INITIALIZED = 1 << 8, FTRACE_OPS_FL_DELETED = 1 << 9, + FTRACE_OPS_FL_SELF_FILTER = 1 << 10, }; /* diff --git a/kernel/kprobes.c b/kernel/kprobes.c index f0ea46c..4f1a72d 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -1037,7 +1037,7 @@ static struct kprobe *alloc_aggr_kprobe(struct kprobe *p) #ifdef CONFIG_KPROBES_ON_FTRACE static struct ftrace_ops kprobe_ftrace_ops __read_mostly = { .func = kprobe_ftrace_handler, - .flags = FTRACE_OPS_FL_SAVE_REGS, + .flags = FTRACE_OPS_FL_SAVE_REGS | FTRACE_OPS_FL_SELF_FILTER, }; static int kprobe_ftrace_enabled; diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 4a54a25..062ca20 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -4501,7 +4501,8 @@ __ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip, */ preempt_disable_notrace(); do_for_each_ftrace_op(op, ftrace_ops_list) { - if (ftrace_ops_test(op, ip, regs)) + if (op->flags & FTRACE_OPS_FL_SELF_FILTER || + ftrace_ops_test(op, ip, regs)) op->func(ip, parent_ip, op, regs); } while_for_each_ftrace_op(op); preempt_enable_notrace();