linux-kernel - [PATCH v2 2/4] perf: streamline append

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Message-Id: <1382107129-2010-3-git-send-email-Waiman.Long@hp.com>
Date:	Fri, 18 Oct 2013 10:38:47 -0400
From:	Waiman Long <Waiman.Long@...com>
To:	Ingo Molnar <mingo@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...stprotocols.net>
Cc:	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Paul Mackerras <paulus@...ba.org>,
	Namhyung Kim <namhyung@...nel.org>,
	Jiri Olsa <jolsa@...hat.com>,
	Adrian Hunter <adrian.hunter@...el.com>,
	David Ahern <dsahern@...il.com>,
	Stephane Eranian <eranian@...gle.com>,
	linux-kernel@...r.kernel.org,
	Aswin Chandramouleeswaran <aswin@...com>,
	Scott J Norton <scott.norton@...com>,
	Waiman Long <Waiman.Long@...com>
Subject: [PATCH v2 2/4] perf: streamline append_chain() function

When callgraph is enabled, the append_chain() function consumes a major
portion of the total CPU time. This patch tries to streamline the
append_chain() function by removing unneeded conditional test as well as
using ?: statement which can be more efficient than the regular if
statement in some architectures.

Signed-off-by: Waiman Long <Waiman.Long@...com>
---
 tools/perf/util/callchain.c |    9 ++++-----
 1 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/tools/perf/util/callchain.c b/tools/perf/util/callchain.c
index 482f680..1e79001 100644
--- a/tools/perf/util/callchain.c
+++ b/tools/perf/util/callchain.c
@@ -315,6 +315,7 @@ append_chain(struct callchain_node *root,
 	struct callchain_list *cnode;
 	u64 start = cursor->pos;
 	bool found = false;
+	bool func_mode = (callchain_param.key == CCKEY_FUNCTION);
 	u64 matches;
 
 	/*
@@ -331,17 +332,15 @@ append_chain(struct callchain_node *root,
 		if (!node)
 			break;
 
-		sym = node->sym;
+		sym = func_mode ? node->sym : NULL;
 
-		if (cnode->ms.sym && sym &&
-		    callchain_param.key == CCKEY_FUNCTION) {
+		if (cnode->ms.sym && sym) {
 			if (cnode->ms.sym->start != sym->start)
 				break;
 		} else if (cnode->ip != node->ip)
 			break;
 
-		if (!found)
-			found = true;
+		found = true;
 
 		callchain_cursor_advance(cursor);
 	}
-- 
1.7.1

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