Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1764017AbXHCWiT (ORCPT ); Fri, 3 Aug 2007 18:38:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1759208AbXHCWiF (ORCPT ); Fri, 3 Aug 2007 18:38:05 -0400 Received: from e33.co.us.ibm.com ([32.97.110.151]:34273 "EHLO e33.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757121AbXHCWiC (ORCPT ); Fri, 3 Aug 2007 18:38:02 -0400 Subject: Re: [PATCH RFC -rt] Allow rcutorture to handle synchronize_sched() From: Josh Triplett To: paulmck@linux.vnet.ibm.com Cc: linux-rt-users@vger.kernel.org, linux-kernel@vger.kernel.org, mingo@elte.hu, dipankar@in.ibm.com, ego@in.ibm.com, vatsa@in.ibm.com In-Reply-To: <20070803184449.GA2196@linux.vnet.ibm.com> References: <20070803184449.GA2196@linux.vnet.ibm.com> Content-Type: text/plain Date: Fri, 03 Aug 2007 15:38:32 -0700 Message-Id: <1186180712.2677.16.camel@josh-work.beaverton.ibm.com> Mime-Version: 1.0 X-Mailer: Evolution 2.6.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 989 Lines: 22 On Fri, 2007-08-03 at 11:44 -0700, Paul E. McKenney wrote: > The rcutorture module uses a random-number generator that periodically > calls get_random_bytes() to add entropy. This random-number generator > is invoked from within the RCU read-side critical section, which, in the > case of the synchronize_sched() variant of RCU, has preeemption disabled. > Unfortunately, get_random_bytes() ends up acquiring normal spinlocks, > which can block in -rt, resulting in very large numbers of "scheduling > while atomic" messages. > > This patch takes a very crude approach, simply substituting the time > of day for get_random_bytes(). > > Signed-off-by: Paul E. McKenney Acked-by: Josh Triplett - 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/