Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932397AbWBAKeX (ORCPT ); Wed, 1 Feb 2006 05:34:23 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932407AbWBAKeX (ORCPT ); Wed, 1 Feb 2006 05:34:23 -0500 Received: from uproxy.gmail.com ([66.249.92.200]:53519 "EHLO uproxy.gmail.com") by vger.kernel.org with ESMTP id S932397AbWBAKeW convert rfc822-to-8bit (ORCPT ); Wed, 1 Feb 2006 05:34:22 -0500 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=Ae+Ogy9tIsMwNO/3yodbvlpi47Pxi1b+TA34E0VCIQqqQ/4AuNBGLqj/bvpjrBhuXuGfRaXsl1kYfXW0/NgqQLjbMXb5Ihz8EKamIS6uADjHlDL++krpPB4ktNmBSohucWRjGbgLLGE2P+GPTBalgT+LdTIXTYxZE6fW1oLoTxU= Message-ID: <58cb370e0602010234p62521a00h6d8920c84cac44d5@mail.gmail.com> Date: Wed, 1 Feb 2006 11:34:18 +0100 From: Bartlomiej Zolnierkiewicz To: Jes Sorensen Subject: Re: [patch] SGIIOC4 limit request size Cc: Alan Cox , Linus Torvalds , linux-kernel@vger.kernel.org, Jeremy Higdon In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT Content-Disposition: inline References: Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2153 Lines: 68 On 01 Feb 2006 03:59:16 -0500, Jes Sorensen wrote: > Hi, Hi, > This one takes care of a problem with the SGI IOC4 driver where it > hits DMA problems if the request grows too large. Does this happen only for CONFIG_IA64_PAGE_SIZE_4KB=y or CONFIG_IA64_PAGE_SIZE_8KB=y? from sgiioc4.c: /* Each Physical Region Descriptor Entry size is 16 bytes (2 * 64 bits) */ /* IOC4 has only 1 IDE channel */ #define IOC4_PRD_BYTES 16 #define IOC4_PRD_ENTRIES (PAGE_SIZE /(4*IOC4_PRD_BYTES)) As limiting request size to 127 sectors punishes performance wouldn't it be better to define IOC4_PRD_ENTRIES to 256 if this is possible (would need 4 pages for PAGE_SIZE=4096 and 2 for PAGE_SIZE=8192)? Cheers. Bartlomiej > Cheers, > Jes > > Avoid requests larger than the number of SG table entries, to avoid > DMA timeouts. > > Signed-off-by: Jes Sorensen > > ---- > > drivers/ide/pci/sgiioc4.c | 8 +++++++- > 1 files changed, 7 insertions(+), 1 deletion(-) > > Index: linux-2.6/drivers/ide/pci/sgiioc4.c > =================================================================== > --- linux-2.6.orig/drivers/ide/pci/sgiioc4.c > +++ linux-2.6/drivers/ide/pci/sgiioc4.c > @@ -1,5 +1,5 @@ > /* > - * Copyright (c) 2003 Silicon Graphics, Inc. All Rights Reserved. > + * Copyright (C) 2003, 2006 Silicon Graphics, Inc. All Rights Reserved. > * > * This program is free software; you can redistribute it and/or modify it > * under the terms of version 2 of the GNU General Public License > @@ -613,6 +613,12 @@ > hwif->ide_dma_lostirq = &sgiioc4_ide_dma_lostirq; > hwif->ide_dma_timeout = &__ide_dma_timeout; > hwif->INB = &sgiioc4_INB; > + > + /* > + * Limit the request size to avoid DMA timeouts when > + * requesting more entries than goes in the sg table. > + */ > + hwif->rqsize = 127; > } > > static int __devinit - 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/