Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752749AbcCRC3J (ORCPT ); Thu, 17 Mar 2016 22:29:09 -0400 Received: from mail-wm0-f41.google.com ([74.125.82.41]:34433 "EHLO mail-wm0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752643AbcCRC3B (ORCPT ); Thu, 17 Mar 2016 22:29:01 -0400 Message-ID: <1458268137.3859.5.camel@gmail.com> Subject: Re: rcu stalls and soft lockups with recent kernels From: Mike Galbraith To: Ion Badulescu , linux-kernel@vger.kernel.org Date: Fri, 18 Mar 2016 03:28:57 +0100 In-Reply-To: <56E9868E.4000006@badula.org> References: <56B39F0C.7070406@badula.org> <56B3A2A8.6000302@badula.org> <56E9868E.4000006@badula.org> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.16.5 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 498 Lines: 13 On Wed, 2016-03-16 at 12:15 -0400, Ion Badulescu wrote: > Just following up to my own email: > > It turns out that we can eliminate the RCU stalls by changing from > CONFIG_RCU_NOCB_CPU_ALL to CONFIG_RCU_NOCB_CPU_NONE. Letting each cpu > handle its own RCU callbacks completely fixes the problems for us. > > Now, CONFIG_NO_HZ_FULL and CONFIG_RCU_NOCB_CPU_ALL is the default config > for fedora and rhel7. Ho-humm... All RCU offloaded to CPU0 of a big box seems like a very bad idea. -Mike