Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755887AbYKEN1c (ORCPT ); Wed, 5 Nov 2008 08:27:32 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753125AbYKEN1X (ORCPT ); Wed, 5 Nov 2008 08:27:23 -0500 Received: from e28smtp07.in.ibm.com ([59.145.155.7]:40738 "EHLO e28smtp07.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752975AbYKEN1W (ORCPT ); Wed, 5 Nov 2008 08:27:22 -0500 From: Sripathi Kodi To: linux-kernel@vger.kernel.org Subject: [PATCH] Inline double_unlock_balance() Date: Wed, 5 Nov 2008 18:57:14 +0530 User-Agent: KMail/1.9.9 Cc: Peter Zijlstra , Steven Rostedt MIME-Version: 1.0 Content-Disposition: inline Message-Id: <200811051857.14944.sripathik@in.ibm.com> Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1647 Lines: 41 Hi, We have a test case which measures the variation in the amount of time needed to perform a fixed amount of work on the preempt_rt kernel. We started seeing deterioration in it's performance recently. The test should never take more than 10 microseconds, but we started 5-10% failure rate. Using elimination method, we traced the problem to commit 1b12bbc747560ea68bcc132c3d05699e52271da0 (lockdep: re-annotate scheduler runqueues). When LOCKDEP is disabled, this patch only adds an additional function call to double_unlock_balance(). Hence I inlined double_unlock_balance() and the problem went away. Here is a patch to make this change. Thanks, Sripathi. lockdep: Inline double_unlock_balance() Additional function call for double_unlock_balance() causes latency problems for some test cases on the preempt_rt kernel. Signed-off-by: Sripathi Kodi Index: linux-2.6.27.4/kernel/sched.c =================================================================== --- linux-2.6.27.4.orig/kernel/sched.c 2008-11-05 05:01:01.000000000 -0800 +++ linux-2.6.27.4/kernel/sched.c 2008-11-05 05:01:20.000000000 -0800 @@ -2812,7 +2812,7 @@ return ret; } -static void double_unlock_balance(struct rq *this_rq, struct rq *busiest) +static inline void double_unlock_balance(struct rq *this_rq, struct rq *busiest) __releases(busiest->lock) { spin_unlock(&busiest->lock); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/