Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755922Ab0GJPnd (ORCPT ); Sat, 10 Jul 2010 11:43:33 -0400 Received: from 8bytes.org ([88.198.83.132]:43008 "EHLO 8bytes.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755717Ab0GJPnc (ORCPT ); Sat, 10 Jul 2010 11:43:32 -0400 Date: Sat, 10 Jul 2010 17:43:31 +0200 From: Joerg Roedel To: Daniel J Blueman Cc: Linus Torvalds , Linux Kernel Subject: Re: [2.6.35-rc3] select useful number of entries for DMA debugging... Message-ID: <20100710154331.GF10080@8bytes.org> References: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1894 Lines: 40 On Sat, Jul 10, 2010 at 03:52:04PM +0100, Daniel J Blueman wrote: > On 9 July 2010 22:33, Linus Torvalds wrote: > > On Mon, Jul 5, 2010 at 1:35 AM, Daniel J Blueman > > wrote: > >> When booting 2.6.35-rc3 on some different x86 boxes with DMA debugging > >> enabled, I've consistently seen it exhaust the allocated entries during > >> boot, giving 'DMA-API: debugging out of memory - disabling'. > >> > >> Increase number of entries to allow DMA debugging again. > > > > Rather than increase the default that gets allocated whenever anybody > > enables the DMA debugging, I'd really prefer to see people use the > > kernel command line option if they run out. After all, it's a (pretty > > esoteric) debug option, and the number of required entries depends on > > machine configuration. I'd rather not make the default cover a huge > > number, when you could just add > > > > ? dma_debug_entries=65536 > > > > on the kernel boot command line instead for machines that want/need it.. > > That said, I am seeing the DMA pool exhaust on a single socket Core i5 > system with Intel graphics and no other adapters - seems like a fairly > common case. If eg 25% of developers will be using similar to this, > maybe it's good to make DMA debugging less immediately esoteric? > > On the other hand, I would immediately agree if the exhaustion > occurred on an atypical setup. How much memory do you have in this machine? We could probably make the number of pre-allocated entries dependent on the memory available in the machine like Ingo suggested some time ago to avoid such problems. Joerg -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/