From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Fri, 28 Sep 2001 15:43:59 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Fri, 28 Sep 2001 15:43:55 -0400 Received: from elin.scali.no ([62.70.89.10]:15378 "EHLO elin.scali.no") by vger.kernel.org with ESMTP id ; Fri, 28 Sep 2001 15:43:35 -0400 Message-ID: <3BB4D202.314C98E6@scali.no> Date: Fri, 28 Sep 2001 21:39:46 +0200 From: Steffen Persvold X-Mailer: Mozilla 4.76 [en] (X11; U; Linux 2.4.2-2 i686) X-Accept-Language: en MIME-Version: 1.0 To: Alan Cox , lkml Subject: Re: mm: critical shortage of bounce buffers In-Reply-To: <3BB4D072.4D3EE56B@scali.no> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Steffen Persvold wrote: > > Alan Cox wrote: > > > > > I've recently encountered the following message on a machine running RedHat's > > > 2.4.3-12 kernel : > > > > > > "mm: critical shortage of bounce buffers" > > > > > > I've searched through the kernel sources, but my 'find' just can't locate this > > > string anywhere. > > > > Its in the high mem handling routines. It means the machine stalled for > > a moment doing I/O because it had no memory below 1Gb to use. > > But why does it need to have memory below 1Gb ?? Normally, 32bit PCI DMA > controllers (such as network cards and disk controllers) can access up to 4GB of > physical memory within the machine, so unless you are using the CONFIG_HIGHMEM4G > option it shouldn't need bounce buffers. Sorry that should have been the CONFIG_HIGHMEM64G option. I think the CONFIG_HIGHMEM4G option could manage without bounce buffers. Regards, -- Steffen Persvold | Scalable Linux Systems | Try out the world's best mailto:sp@scali.no | http://www.scali.com | performing MPI implementation: Tel: (+47) 2262 8950 | Olaf Helsets vei 6 | - ScaMPI 1.12.2 - Fax: (+47) 2262 8951 | N0621 Oslo, NORWAY | >300MBytes/s and <4uS latency