From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f54.google.com (mail-pa0-f54.google.com [209.85.220.54]) by kanga.kvack.org (Postfix) with ESMTP id 20D8F6B0038 for ; Wed, 27 Aug 2014 19:06:13 -0400 (EDT) Received: by mail-pa0-f54.google.com with SMTP id fb1so109434pad.27 for ; Wed, 27 Aug 2014 16:06:12 -0700 (PDT) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org. [140.211.169.12]) by mx.google.com with ESMTPS id gr4si2898930pac.196.2014.08.27.16.06.11 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 27 Aug 2014 16:06:12 -0700 (PDT) Date: Wed, 27 Aug 2014 16:06:10 -0700 From: Andrew Morton 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> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: 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 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? -- 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