From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757514AbYCASgo (ORCPT ); Sat, 1 Mar 2008 13:36:44 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752362AbYCASgd (ORCPT ); Sat, 1 Mar 2008 13:36:33 -0500 Received: from brick.kernel.dk ([87.55.233.238]:18144 "EHLO kernel.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751943AbYCASgc (ORCPT ); Sat, 1 Mar 2008 13:36:32 -0500 Date: Sat, 1 Mar 2008 19:36:28 +0100 From: Jens Axboe To: petkovbb@gmail.com, bzolnier@gmail.com, linux-ide@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 00/24] ide-tape: remove pipelined mode operation Message-ID: <20080301183627.GB6704@kernel.dk> References: <1204361928-30229-1-git-send-email-petkovbb@gmail.com> <20080301095518.GW6704@kernel.dk> <20080301154529.GB30547@gollum.tnic> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080301154529.GB30547@gollum.tnic> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Mar 01 2008, Borislav Petkov wrote: > On Sat, Mar 01, 2008 at 10:55:18AM +0100, Jens Axboe wrote: > > On Sat, Mar 01 2008, Borislav Petkov wrote: > > > Hi Bart, > > > > > > here's the 1st draft of the pipeline removal series. As the diffstat below openly > > > states it, a lot of code got removed - even more than the cleanup series we did > > > earlier. There are several issues that we need to address concerning these > > > patches: > > > > > > 1. only compile-tested since i don't have the hardware, i.e. longer -mm brewing is > > > advisable the least. > > > > > > 2. I have left the tape->merge_stage buffer structure along with its > > > alloc/free functions intact for now, for simplicity. The next step would be > > > to go and carefully audit the code and then remove that last piece > > > too and use allocations on the stack instead. I guess we still expect > > > Jens's response on whether blk_{get,put}_request is the way to go here. > > > > > > Jens? > > > > Hm, I have not seen any questions regarding this directed my way :-) > > Please point me to the original question and I'll take a look at it. > > Hi Jens, > > sorry but maybe we weren't that explicit, here's a pointer to the > relevant thread: > http://www.mail-archive.com/linux-ide@vger.kernel.org/msg15541.html. > It boils down to removing the statically allocated arrays of buffers > for pc and rq structs in ide-floppy and ide-tape, and using GFP_ATOMIC > stack memory instead. Bart's idea was to even go a step further and > even avoid allocation errors in out-of-mem situations by reusing > requests from the request queue but wasn't sure whether this'll fly > and wanted to run it by you... That sounds like asking for trouble, if you ask me (well you did :-) And being a very rarely exercised path (if at all, you should be very unlucky to NOT get a request even with GFP_ATOMIC), then it wont even get tested properly. So I'd say stick to GFP_ATOMIC, and just plug the device and retry if you get into allocation errors. -- Jens Axboe