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From: Steven Rostedt <rostedt@goodmis.org>
To: linux-kernel@vger.kernel.org
Cc: Ingo Molnar <mingo@elte.hu>,
	Andrew Morton <akpm@linux-foundation.org>,
	Tom Zanussi <tzanussi@gmail.com>,
	Frederic Weisbecker <fweisbec@gmail.com>,
	Lai Jiangshan <laijs@cn.fujitsu.com>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Subject: [RFC][PATCH 08/12] tracing/filter: Optimize short ciruit check
Date: Thu, 27 Jan 2011 23:21:26 -0500	[thread overview]
Message-ID: <20110128043345.224997318@goodmis.org> (raw)
In-Reply-To: 20110128042118.561146147@goodmis.org

[-- Attachment #1: 0008-tracing-filter-Optimize-short-ciruit-check.patch --]
[-- Type: text/plain, Size: 1406 bytes --]

From: Steven Rostedt <srostedt@redhat.com>

The test if we should break out early for OR and AND operations
can be optimized by comparing the current result with
  (pred->op == OP_OR)

That is if the result is true and the op is an OP_OR, or
if the result is false and the op is not an OP_OR (thus an OP_AND)
we can break out early in either case. Otherwise we continue
processing.

Cc: Tom Zanussi <tzanussi@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 kernel/trace/trace_events_filter.c |   12 +++++++++---
 1 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index 2677924..afe59ab 100644
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -426,9 +426,15 @@ int filter_match_preds(struct event_filter *filter, void *rec)
 					       pred->parent, &move);
 			continue;
 		case MOVE_UP_FROM_LEFT:
-			/* Check for short circuits */
-			if ((match && pred->op == OP_OR) ||
-			    (!match && pred->op == OP_AND)) {
+			/*
+			 * Check for short circuits.
+			 *
+			 * Optimization: !!match == (pred->op == OP_OR)
+			 *   is the same as:
+			 * if ((match && pred->op == OP_OR) ||
+			 *     (!match && pred->op == OP_AND))
+			 */
+			if (!!match == (pred->op == OP_OR))
 				if (pred == root)
 					break;
 				pred = get_pred_parent(pred, preds,
-- 
1.7.2.3



  parent reply	other threads:[~2011-01-28  4:34 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-01-28  4:21 [RFC][PATCH 00/12] tracing/filter: Remove 32 pred limit and add short circuits Steven Rostedt
2011-01-28  4:21 ` [RFC][PATCH 01/12] tracing/filter: Have no filter return a match Steven Rostedt
2011-01-28  4:21 ` [RFC][PATCH 02/12] tracing/filter: Move OR and AND logic out of fn() method Steven Rostedt
2011-01-28  4:21 ` [RFC][PATCH 03/12] tracing/filter: Dynamically allocate preds Steven Rostedt
2011-01-28  4:21 ` [RFC][PATCH 04/12] tracing/filter: Call synchronize_sched() just once for system filters Steven Rostedt
2011-01-28  4:21 ` [RFC][PATCH 05/12] tracing/filter: Allocate the preds in an array Steven Rostedt
2011-01-28  4:21 ` [RFC][PATCH 06/12] tracing/filter: Free pred array on disabling of filter Steven Rostedt
2011-01-28  4:21 ` [RFC][PATCH 07/12] tracing/filter: Use a tree instead of stack for filter_match_preds() Steven Rostedt
2011-01-28  4:21 ` Steven Rostedt [this message]
2011-01-28  5:37   ` [RFC][PATCH 08/12] tracing/filter: Optimize short ciruit check Steven Rostedt
2011-01-28  4:21 ` [RFC][PATCH 09/12] tracing/filter: Check the created pred tree Steven Rostedt
2011-01-28  4:21 ` [RFC][PATCH 10/12] tracing/filter: Optimize filter by folding the tree Steven Rostedt
2011-01-28  4:21 ` [RFC][PATCH 11/12] tracing/filter: Move MAX_FILTER_PRED to local tracing directory Steven Rostedt
2011-01-28  4:21 ` [RFC][PATCH 12/12] tracing/filter: Increase the max preds to 2^14 Steven Rostedt

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