Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932488AbVLUSRh (ORCPT ); Wed, 21 Dec 2005 13:17:37 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932489AbVLUSRh (ORCPT ); Wed, 21 Dec 2005 13:17:37 -0500 Received: from hera.kernel.org ([140.211.167.34]:23269 "EHLO hera.kernel.org") by vger.kernel.org with ESMTP id S932488AbVLUSRg (ORCPT ); Wed, 21 Dec 2005 13:17:36 -0500 Date: Wed, 21 Dec 2005 16:17:32 -0200 From: Marcelo Tosatti To: Christoph Hellwig , Dan Aloni , Luke-Jr , Linux Kernel Mailing List Subject: Re: [PATCH 2.4.x] prevent emulated SCSI hosts from wasting DMA memory Message-ID: <20051221181732.GC28272@dmt.cnet> References: <20051130171520.GB15505@localdomain> <200511301933.48668.luke-jr@utopios.org> <20051130210222.GA32431@localdomain> <20051201113610.GG3958@infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20051201113610.GG3958@infradead.org> User-Agent: Mutt/1.4.2.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1357 Lines: 26 On Thu, Dec 01, 2005 at 11:36:10AM +0000, Christoph Hellwig wrote: > On Wed, Nov 30, 2005 at 11:02:23PM +0200, Dan Aloni wrote: > > On Wed, Nov 30, 2005 at 07:33:47PM +0000, Luke-Jr wrote: > > > On Wednesday 30 November 2005 17:15, Dan Aloni wrote: > > > > Emulated scsi hosts don't do DMA, so don't unnecessarily increase > > > > the SCSI DMA pool. > > > > > > They don't? Recently I learned(?) that apparently using hdparm -d on the > > > old /dev/hdX device still worked/applied when using ide-scsi... or do > > > "emulated scsi hosts" refer to something else? > > > > Actually by 'do DMA' I meant use the scsi_malloc() interface - which > > is mostly used by low level drivers. The IDE drivers allocate their > > DMA memory outside the SCSI layer. iSCSI hosts for instance, don't > > need to cause unnecessary DMA allocations. > > (1) there's no guranteee a driver setting ->emulated can't use scsi_malloc > (2) 2.4.x is very late in the cycle so there's just no point in putting this > in (and in 2.6.x scsi_malloc is gone fortunately) Agreed - this does not sound like a critical bug fix to me. - 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/