From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965188AbaH0XGQ (ORCPT ); Wed, 27 Aug 2014 19:06:16 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:58993 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964957AbaH0XGM (ORCPT ); Wed, 27 Aug 2014 19:06:12 -0400 Date: Wed, 27 Aug 2014 16:06:10 -0700 From: Andrew Morton To: Mike Travis Cc: mingo@redhat.com, tglx@linutronix.de, hpa@zytor.com, msalter@redhat.com, dyoung@redhat.com, riel@redhat.com, peterz@infradead.org, mgorman@suse.de, linux-kernel@vger.kernel.org, x86@kernel.org, linux-mm@kvack.org Subject: Re: [PATCH 0/2] x86: Speed up ioremap operations Message-Id: <20140827160610.4ef142d28fd7f276efd38a51@linux-foundation.org> In-Reply-To: <20140827225927.364537333@asylum.americas.sgi.com> References: <20140827225927.364537333@asylum.americas.sgi.com> X-Mailer: Sylpheed 3.2.0beta5 (GTK+ 2.24.10; x86_64-pc-linux-gnu) Mime-Version: 1.0 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 On Wed, 27 Aug 2014 17:59:27 -0500 Mike Travis wrote: > > We have a large university system in the UK that is experiencing > very long delays modprobing the driver for a specific I/O device. > The delay is from 8-10 minutes per device and there are 31 devices > in the system. This 4 to 5 hour delay in starting up those I/O > devices is very much a burden on the customer. That's nuts. > There are two causes for requiring a restart/reload of the drivers. > First is periodic preventive maintenance (PM) and the second is if > any of the devices experience a fatal error. Both of these trigger > this excessively long delay in bringing the system back up to full > capability. > > The problem was tracked down to a very slow IOREMAP operation and > the excessively long ioresource lookup to insure that the user is > not attempting to ioremap RAM. These patches provide a speed up > to that function. With what result?