From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f48.google.com (mail-pa0-f48.google.com [209.85.220.48]) by kanga.kvack.org (Postfix) with ESMTP id 8A94E6B0044 for ; Fri, 29 Aug 2014 15:53:37 -0400 (EDT) Received: by mail-pa0-f48.google.com with SMTP id ey11so7185712pad.21 for ; Fri, 29 Aug 2014 12:53:37 -0700 (PDT) Received: from relay.sgi.com (relay3.sgi.com. [192.48.152.1]) by mx.google.com with ESMTP id oa7si1744568pdb.178.2014.08.29.12.53.35 for ; Fri, 29 Aug 2014 12:53:35 -0700 (PDT) Message-Id: <20140829195328.511550688@asylum.americas.sgi.com> Date: Fri, 29 Aug 2014 14:53:28 -0500 From: Mike Travis Subject: [PATCH 0/2] x86: Speed up ioremap operations Sender: owner-linux-mm@kvack.org List-ID: To: mingo@redhat.com, tglx@linutronix.de, hpa@zytor.com Cc: akpm@linux-foundation.org, 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 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. 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. -- -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org