From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ie0-f173.google.com (mail-ie0-f173.google.com [209.85.223.173]) by kanga.kvack.org (Postfix) with ESMTP id DF0D16B0037 for ; Wed, 27 Aug 2014 18:59:30 -0400 (EDT) Received: by mail-ie0-f173.google.com with SMTP id lx4so184421iec.32 for ; Wed, 27 Aug 2014 15:59:30 -0700 (PDT) Received: from relay.sgi.com (relay1.sgi.com. [192.48.180.66]) by mx.google.com with ESMTP id x6si7442067igr.45.2014.08.27.15.59.29 for ; Wed, 27 Aug 2014 15:59:29 -0700 (PDT) Message-Id: <20140827225927.364537333@asylum.americas.sgi.com> Date: Wed, 27 Aug 2014 17:59:27 -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