Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751855Ab0GKLye (ORCPT ); Sun, 11 Jul 2010 07:54:34 -0400 Received: from mail-gx0-f174.google.com ([209.85.161.174]:34459 "EHLO mail-gx0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751506Ab0GKLyc convert rfc822-to-8bit (ORCPT ); Sun, 11 Jul 2010 07:54:32 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=acpxGrctY0OUFd9qqj/yD2e+KGsHzTv8bSUlA54lvoq906kaaoytN9V6CBhD6KLTax EC+Ignp6MatQLJbMRGG6ghDGLEPKXTVTz9ds0t2QppXqxSJY/U7VqSgShPbObJPTVPqX 3aHDMWIMI+M67oCDs0Tas8f1x4Y3oWTg8xZXQ= MIME-Version: 1.0 In-Reply-To: <20100710154331.GF10080@8bytes.org> References: <20100710154331.GF10080@8bytes.org> Date: Sun, 11 Jul 2010 12:54:31 +0100 Message-ID: Subject: Re: [2.6.35-rc3] select useful number of entries for DMA debugging... From: Daniel J Blueman To: Joerg Roedel Cc: Linus Torvalds , Linux Kernel Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2235 Lines: 45 On 10 July 2010 16:43, Joerg Roedel wrote: > 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. I have 4GB. Since this change is specific to x86, I guess the only corner case we need to protect from this change is developers on small x86 embedded systems such as MIDs, so lowering the allocated size on <1GB systems makes sense. -- Daniel J Blueman -- 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/