From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933253AbaD2A0E (ORCPT ); Mon, 28 Apr 2014 20:26:04 -0400 Received: from e31.co.us.ibm.com ([32.97.110.149]:52010 "EHLO e31.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933039AbaD2AZt (ORCPT ); Mon, 28 Apr 2014 20:25:49 -0400 From: "Paul E. McKenney" To: linux-kernel@vger.kernel.org Cc: mingo@kernel.org, laijs@cn.fujitsu.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, niv@us.ibm.com, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, darren@dvhart.com, fweisbec@gmail.com, oleg@redhat.com, sbw@mit.edu, "Paul E. McKenney" Subject: [PATCH tip/core/rcu 22/45] torture: Increase stutter-end intensity Date: Mon, 28 Apr 2014 17:25:10 -0700 Message-Id: <1398731133-18925-22-git-send-email-paulmck@linux.vnet.ibm.com> X-Mailer: git-send-email 1.8.1.5 In-Reply-To: <1398731133-18925-1-git-send-email-paulmck@linux.vnet.ibm.com> References: <20140429002455.GA15461@linux.vnet.ibm.com> <1398731133-18925-1-git-send-email-paulmck@linux.vnet.ibm.com> X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 14042900-8236-0000-0000-000001E64A76 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Paul E. McKenney" Currently, all stuttered kthreads block a jiffy at a time, which can result in them starting at different times. (Note: This is not an energy-efficiency problem unless you run torture tests in production, in which case you have other problems!) This commit increases the intensity of the restart event by causing kthreads to spin through the last jiffy, restarting when they see the variable change. Signed-off-by: Paul E. McKenney --- kernel/torture.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/kernel/torture.c b/kernel/torture.c index f329848c3eee..bd768effba9a 100644 --- a/kernel/torture.c +++ b/kernel/torture.c @@ -533,7 +533,11 @@ void stutter_wait(const char *title) while (ACCESS_ONCE(stutter_pause_test) || (torture_runnable && !ACCESS_ONCE(*torture_runnable))) { if (stutter_pause_test) - schedule_timeout_interruptible(1); + if (ACCESS_ONCE(stutter_pause_test) == 1) + schedule_timeout_interruptible(1); + else + while (ACCESS_ONCE(stutter_pause_test)) + cond_resched(); else schedule_timeout_interruptible(round_jiffies_relative(HZ)); torture_shutdown_absorb(title); @@ -550,7 +554,11 @@ static int torture_stutter(void *arg) VERBOSE_TOROUT_STRING("torture_stutter task started"); do { if (!torture_must_stop()) { - schedule_timeout_interruptible(stutter); + if (stutter > 1) { + schedule_timeout_interruptible(stutter - 1); + ACCESS_ONCE(stutter_pause_test) = 2; + } + schedule_timeout_interruptible(1); ACCESS_ONCE(stutter_pause_test) = 1; } if (!torture_must_stop()) -- 1.8.1.5