From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jens Axboe Subject: Re: [PATCH 2/2] drop vmerge accounting Date: Fri, 15 Aug 2008 11:48:00 +0200 Message-ID: <20080815094800.GI20055@kernel.dk> References: <20080808055405.GF20055@kernel.dk> <20080808151147J.fujita.tomonori@lab.ntt.co.jp> <20080808061537.GI20055@kernel.dk> <20080808152845N.fujita.tomonori@lab.ntt.co.jp> <20080808063527.GJ20055@kernel.dk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from brick.kernel.dk ([87.55.233.238]:2587 "EHLO kernel.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751865AbYHOJsC (ORCPT ); Fri, 15 Aug 2008 05:48:02 -0400 Content-Disposition: inline In-Reply-To: Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Mikulas Patocka Cc: FUJITA Tomonori , adel.gadllah@gmail.com, matthew@wil.cx, linux-scsi@vger.kernel.org, James.Bottomley@hansenpartnership.com, dan.j.williams@intel.com, pjones@redhat.com, viro@zeniv.linux.org.uk, dougg@torque.net On Fri, Aug 08 2008, Mikulas Patocka wrote: > On Fri, 8 Aug 2008, Mikulas Patocka wrote: > > > On Fri, 8 Aug 2008, Jens Axboe wrote: > > > > > On Fri, Aug 08 2008, FUJITA Tomonori wrote: > > > > On Fri, 8 Aug 2008 08:15:37 +0200 > > > > Jens Axboe wrote: > > > > > > > > > > BTW, we also wait for your verdict on: > > > > > > > > > > > > http://marc.info/?t=121611935500002&r=1&w=2 > > > > > > > > > > I've always hated the iommu virtual merging complexity. My plan is to > > > > > rip it out. > > > > > > > > No complaint from me. I'm just happy to see the verdict at length. > > > > > > Mikulas, you had a patch for this. Can you strip out the arch bits and > > > just send me the block bits? The arch bits should go in via the arch > > > maintainers. > > > > > > The iommu code may still do virtual merging, it would be silly not to do > > > that if possible. Now that later kernels expose the necessary parameters > > > at that level as well, it's perfectly feasible. > > > > Here I'm sending the first one, it removes virtual merge accounting from > > blk-merge.c (it acts as if all architectures undefined > > BIO_VMERGE_BOUNDARY). I also created second patch that removes > > bi_hw_segments field from struct bio and struct request. The next task > > would be to remove nr_hw_segments from the request_queue, but it will > > require changing the drivers. > > > > Mikulas > > (note: raid5 uses nr_hw_segments field for some other purpose, so this > patch will break it. It should be fixed by raid5 maintainers) > > Remove hw_segments field from struct bio and struct request. Without virtual > merge accounting they have no purpose. I have applied this and the previous, with a fixup to raid5 to overload both active stripe and process count in bi_phys_segments. -- Jens Axboe