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From: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
To: linux-kernel@vger.kernel.org, Ingo Molnar <mingo@kernel.org>
Cc: Andi Kleen <andi@firstfloor.org>,
	Ananth N Mavinakayanahalli <ananth@in.ibm.com>,
	Sandeepa Prabhu <sandeepa.prabhu@linaro.org>,
	Frederic Weisbecker <fweisbec@gmail.com>,
	x86@kernel.org, Steven Rostedt <rostedt@goodmis.org>,
	fche@redhat.com, mingo@redhat.com, systemtap@sourceware.org,
	"H. Peter Anvin" <hpa@zytor.com>,
	Thomas Gleixner <tglx@linutronix.de>
Subject: [PATCH -tip v9 26/26] ftrace: Introduce FTRACE_OPS_FL_SELF_FILTER for ftrace-kprobe
Date: Thu, 17 Apr 2014 17:19:38 +0900
Message-ID: <20140417081937.26341.73274.stgit@ltc230.yrl.intra.hitachi.co.jp> (raw)
In-Reply-To: <20140417081636.26341.87858.stgit@ltc230.yrl.intra.hitachi.co.jp>

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 v7:
 - Re-evaluate the performance improvement.

Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
---
 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 9212b01..36e4cb5 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 filters ip by itself. Do not need to
+ *            check hash table on each hit.
  */
 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 465e912..af1ff6a 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -1020,7 +1020,7 @@ 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 1fd4b94..4235851 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -4520,7 +4520,8 @@ __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();



  parent reply index

Thread overview: 103+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-04-17  8:16 [PATCH -tip v9 00/26] kprobes: introduce NOKPROBE_SYMBOL, bugfixes and scalbility efforts Masami Hiramatsu
2014-04-17  8:16 ` [PATCH -tip v9 01/26] [BUGFIX]kprobes/x86: Fix page-fault handling logic Masami Hiramatsu
2014-04-17  9:58   ` [tip:perf/urgent] kprobes/x86: " tip-bot for Masami Hiramatsu
2014-04-17  8:16 ` [PATCH -tip v9 02/26] kprobes/x86: Allow to handle reentered kprobe on singlestepping Masami Hiramatsu
2014-04-24 10:57   ` [tip:perf/kprobes] kprobes/x86: Allow to handle reentered kprobe on single-stepping tip-bot for Masami Hiramatsu
2014-04-17  8:16 ` [PATCH -tip v9 03/26] kprobes: Prohibit probing on .entry.text code Masami Hiramatsu
2014-04-24 10:57   ` [tip:perf/kprobes] " tip-bot for Masami Hiramatsu
2014-04-17  8:17 ` [PATCH -tip v9 04/26] kprobes: Introduce NOKPROBE_SYMBOL() macro for blacklist Masami Hiramatsu
2014-04-24 10:58   ` [tip:perf/kprobes] kprobes: Introduce NOKPROBE_SYMBOL() macro to maintain kprobes blacklist tip-bot for Masami Hiramatsu
2014-05-01  5:26     ` kprobes broken in linux-next (was Re: [tip:perf/kprobes] kprobes: Introduce NOKPROBE_SYMBOL() macro to maintain kprobes blacklist) Vineet Gupta
2014-05-02  1:13       ` Masami Hiramatsu
2014-05-07  4:56         ` Vineet Gupta
2014-05-07 19:18       ` [tip:perf/kprobes] kprobes: Ensure blacklist data is aligned tip-bot for Vineet Gupta
2014-05-05 20:48     ` [tip:perf/kprobes] kprobes: Introduce NOKPROBE_SYMBOL() macro to maintain kprobes blacklist Tony Luck
2014-05-06  9:25       ` Masami Hiramatsu
2014-05-06 10:03       ` Masami Hiramatsu
2014-05-07 11:19         ` Masami Hiramatsu
2014-05-07 11:55           ` [RFT PATCH -next ] [BUGFIX] kprobes: Fix "Failed to find blacklist" error on ia64 and ppc64 Masami Hiramatsu
2014-05-07 11:59             ` Masami Hiramatsu
2014-05-14  8:19               ` Masami Hiramatsu
2014-05-08  4:47             ` Ananth N Mavinakayanahalli
2014-05-08  5:40               ` Masami Hiramatsu
2014-05-08  6:16                 ` Ananth N Mavinakayanahalli
2014-05-09  8:06                   ` Masami Hiramatsu
2014-05-26 11:25             ` Suzuki K. Poulose
2014-05-26 11:48               ` Masami Hiramatsu
2014-05-27  6:31               ` [RFT PATCH -next v2] " Masami Hiramatsu
2014-05-29 19:13                 ` Suzuki K. Poulose
2014-05-30  2:47                   ` Masami Hiramatsu
2014-05-30  3:18                     ` [RFT PATCH -next v3] " Masami Hiramatsu
2014-06-06  6:38                       ` Masami Hiramatsu
2014-06-17 23:03                         ` Tony Luck
2014-06-18  7:56                         ` Michael Ellerman
2014-06-18  8:46                           ` Masami Hiramatsu
2014-06-19  1:30                             ` Michael Ellerman
2014-06-19  4:52                               ` Masami Hiramatsu
2014-06-19  6:40                                 ` Suzuki K. Poulose
2014-06-19  7:26                                   ` Masami Hiramatsu
2014-06-19  9:45                                     ` Suzuki K. Poulose
2014-06-19 11:01                                       ` Masami Hiramatsu
2014-06-19 11:20                                         ` Masami Hiramatsu
2014-06-20  0:37                                           ` Michael Ellerman
2014-06-20  2:13                                             ` Masami Hiramatsu
2014-04-17  8:17 ` [PATCH -tip v9 05/26] [BUGFIX] kprobes/x86: Prohibit probing on debug_stack_* Masami Hiramatsu
2014-04-24 10:58   ` [tip:perf/kprobes] kprobes, x86: Prohibit probing on debug_stack_*() tip-bot for Masami Hiramatsu
2014-04-17  8:17 ` [PATCH -tip v9 06/26] [BUGFIX] x86: Prohibit probing on native_set_debugreg/load_idt Masami Hiramatsu
2014-04-24 10:58   ` [tip:perf/kprobes] kprobes, x86: Prohibit probing on native_set_debugreg()/load_idt() tip-bot for Masami Hiramatsu
2014-04-17  8:17 ` [PATCH -tip v9 07/26] [BUGFIX] x86: Prohibit probing on thunk functions and restore Masami Hiramatsu
2014-04-24 10:58   ` [tip:perf/kprobes] kprobes, " tip-bot for Masami Hiramatsu
2014-04-17  8:17 ` [PATCH -tip v9 08/26] kprobes/x86: Call exception handlers directly from do_int3/do_debug Masami Hiramatsu
2014-04-24 10:59   ` [tip:perf/kprobes] " tip-bot for Masami Hiramatsu
2014-04-24 11:26     ` Jiri Kosina
2014-04-17  8:17 ` [PATCH -tip v9 09/26] x86: Call exception_enter after kprobes handled Masami Hiramatsu
2014-04-24 10:59   ` [tip:perf/kprobes] kprobes, " tip-bot for Masami Hiramatsu
2014-06-13 17:14     ` Frederic Weisbecker
2014-06-14  5:44       ` Masami Hiramatsu
2014-06-14  6:47         ` [PATCH -tip ] [Bugfix] x86/kprobes: Fix build errors and blacklist context_track_user Masami Hiramatsu
2014-06-14  8:58           ` [tip:perf/urgent] " tip-bot for Masami Hiramatsu
2014-06-16 15:52           ` [PATCH -tip ] [Bugfix] " Frederic Weisbecker
2014-04-17  8:17 ` [PATCH -tip v9 10/26] kprobes/x86: Allow probe on some kprobe preparation functions Masami Hiramatsu
2014-04-24 10:59   ` [tip:perf/kprobes] " tip-bot for Masami Hiramatsu
2014-04-17  8:17 ` [PATCH -tip v9 11/26] kprobes: Allow probe on some kprobe functions Masami Hiramatsu
2014-04-24 10:59   ` [tip:perf/kprobes] " tip-bot for Masami Hiramatsu
2014-04-17  8:18 ` [PATCH -tip v9 12/26] ftrace/*probes: Allow probing on some functions Masami Hiramatsu
2014-04-24 10:59   ` [tip:perf/kprobes] kprobes, ftrace: " tip-bot for Masami Hiramatsu
2014-04-17  8:18 ` [PATCH -tip v9 13/26] x86: Allow kprobes on text_poke/hw_breakpoint Masami Hiramatsu
2014-04-24 11:00   ` [tip:perf/kprobes] kprobes, x86: Allow kprobes on text_poke/ hw_breakpoint tip-bot for Masami Hiramatsu
2014-04-24 11:26     ` Jiri Kosina
2014-04-17  8:18 ` [PATCH -tip v9 14/26] x86: Use NOKPROBE_SYMBOL() instead of __kprobes annotation Masami Hiramatsu
2014-04-24 11:00   ` [tip:perf/kprobes] kprobes, " tip-bot for Masami Hiramatsu
2014-04-17  8:18 ` [PATCH -tip v9 15/26] kprobes: Use NOKPROBE_SYMBOL macro instead of __kprobes Masami Hiramatsu
2014-04-24 11:00   ` [tip:perf/kprobes] " tip-bot for Masami Hiramatsu
2014-04-17  8:18 ` [PATCH -tip v9 16/26] ftrace/kprobes: Use NOKPROBE_SYMBOL macro in ftrace Masami Hiramatsu
2014-04-24 11:00   ` [tip:perf/kprobes] kprobes, ftrace: " tip-bot for Masami Hiramatsu
2014-04-17  8:18 ` [PATCH -tip v9 17/26] notifier: Use NOKPROBE_SYMBOL macro in notifier Masami Hiramatsu
2014-04-17 14:40   ` Josh Triplett
2014-04-24 11:00   ` [tip:perf/kprobes] kprobes, " tip-bot for Masami Hiramatsu
2014-04-17  8:18 ` [PATCH -tip v9 18/26] sched: Use NOKPROBE_SYMBOL macro in sched Masami Hiramatsu
2014-04-24 11:01   ` [tip:perf/kprobes] kprobes, " tip-bot for Masami Hiramatsu
2014-04-17  8:18 ` [PATCH -tip v9 19/26] kprobes: Show blacklist entries via debugfs Masami Hiramatsu
2014-04-24 11:01   ` [tip:perf/kprobes] " tip-bot for Masami Hiramatsu
2014-04-17  8:18 ` [PATCH -tip v9 20/26] kprobes: Support blacklist functions in module Masami Hiramatsu
2014-04-24  8:56   ` Ingo Molnar
2014-04-24 11:24     ` Masami Hiramatsu
2014-04-25  8:19       ` Ingo Molnar
2014-04-25 10:12         ` Masami Hiramatsu
2014-04-25 10:55           ` Masami Hiramatsu
2014-04-17  8:19 ` [PATCH -tip v9 21/26] kprobes: Use NOKPROBE_SYMBOL() in sample modules Masami Hiramatsu
2014-04-17  8:19 ` [PATCH -tip v9 22/26] kprobes/x86: Use kprobe_blacklist for .kprobes.text and .entry.text Masami Hiramatsu
2014-04-24  8:58   ` Ingo Molnar
2014-04-24 11:22     ` Masami Hiramatsu
2014-04-17  8:19 ` [PATCH -tip v9 23/26] kprobes/x86: Remove unneeded preempt_disable/enable in interrupt handlers Masami Hiramatsu
2014-04-17  8:19 ` [PATCH -tip v9 24/26] kprobes: Enlarge hash table to 512 entries Masami Hiramatsu
2014-04-17  8:19 ` [PATCH -tip v9 25/26] kprobes: Introduce kprobe cache to reduce cache misshits Masami Hiramatsu
2014-04-24  9:01   ` Ingo Molnar
2014-04-24 11:38     ` Masami Hiramatsu
2014-04-25  8:20       ` Ingo Molnar
2014-04-25  9:43         ` Masami Hiramatsu
2014-04-26  7:12           ` Ingo Molnar
2014-04-27 12:49             ` Masami Hiramatsu
2014-04-17  8:19 ` Masami Hiramatsu [this message]
2014-04-17  8:37 ` [PATCH -tip v9 00/26] kprobes: introduce NOKPROBE_SYMBOL, bugfixes and scalbility efforts Ingo Molnar
2014-04-17  8:53   ` Masami Hiramatsu

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