From mboxrd@z Thu Jan 1 00:00:00 1970 From: paulmck@linux.vnet.ibm.com (Paul E. McKenney) Date: Fri, 21 Sep 2012 15:03:03 -0700 Subject: rcu self-detected stall messages on OMAP3, 4 boards In-Reply-To: <20120921203149.GI28835@atomide.com> References: <20120920220130.GN2449@linux.vnet.ibm.com> <20120920232114.GO2449@linux.vnet.ibm.com> <20120921185827.GC2454@linux.vnet.ibm.com> <20120921195717.GD2454@linux.vnet.ibm.com> <20120921203149.GI28835@atomide.com> Message-ID: <20120921220302.GF2454@linux.vnet.ibm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Fri, Sep 21, 2012 at 01:31:49PM -0700, Tony Lindgren wrote: > * Paul E. McKenney [120921 12:58]: > > > > Just to make sure I understand the combinations: > > > > o All stalls have happened when running a minimal userspace. > > o CONFIG_NO_HZ=n suppresses the stalls. > > o CONFIG_RCU_FAST_NO_HZ (which depends on CONFIG_NO_HZ=y) has > > no observable effect on the stalls. > > The reason why you may need minimal userspace is to cut down > the number of timers waking up the system with NO_HZ. > Booting with init=/bin/sh might also do the trick for that. Good point! This does make for a very quiet system, but does not reproduce the problem under kvm, even after waiting for four minutes. I will leave it for more time, but it looks like I really might need to ask Linaro for remote access to a Panda. Thanx, Paul