From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933024Ab2AFJKq (ORCPT ); Fri, 6 Jan 2012 04:10:46 -0500 Received: from LGEMRELSE1Q.lge.com ([156.147.1.111]:61240 "EHLO LGEMRELSE1Q.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757469Ab2AFJKl (ORCPT ); Fri, 6 Jan 2012 04:10:41 -0500 X-AuditID: 9c93016f-b7c8eae000000e9e-be-4f06ba7f03b7 Message-ID: <4F06BA78.30606@lge.com> Date: Fri, 06 Jan 2012 18:10:16 +0900 From: Namhyung Kim User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:8.0) Gecko/20111105 Thunderbird/8.0 MIME-Version: 1.0 To: Shaohua Li CC: Dave Chinner , linux-kernel@vger.kernel.org, axboe@kernel.dk, vgoyal@redhat.com, jmoyer@redhat.com Subject: Re: [RFC 0/3]block: An IOPS based ioscheduler References: <20120104065337.230911609@sli10-conroe.sh.intel.com> <20120104071931.GB17026@dastard> <1325746241.22361.503.camel@sli10-conroe> <1325826750.22361.533.camel@sli10-conroe> In-Reply-To: <1325826750.22361.533.camel@sli10-conroe> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Brightmail-Tracker: AAAAAA== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2012-01-06 PM 2:12, Shaohua Li wrote: > On Thu, 2012-01-05 at 14:50 +0800, Shaohua Li wrote: >> On Wed, 2012-01-04 at 18:19 +1100, Dave Chinner wrote: >>> On Wed, Jan 04, 2012 at 02:53:37PM +0800, Shaohua Li wrote: >>>> An IOPS based I/O scheduler >>>> >>>> Flash based storage has some different characteristics against rotate disk. >>>> 1. no I/O seek. >>>> 2. read and write I/O cost usually is much different. >>>> 3. Time which a request takes depends on request size. >>>> 4. High throughput and IOPS, low latency. >>>> >>>> CFQ iosched does well for rotate disk, for example fair dispatching, idle >>>> for sequential read. It also has optimization for flash based storage (for >>>> item 1 above), but overall it's not designed for flash based storage. It's >>>> a slice based algorithm. Since flash based storage request cost is very >>>> low, and drive has big queue_depth is quite popular now which makes >>>> dispatching cost even lower, CFQ's slice accounting (jiffy based) >>>> doesn't work well. CFQ doesn't consider above item 2& 3. >>>> >>>> FIOPS (Fair IOPS) ioscheduler is trying to fix the gaps. It's IOPS based, so >>>> only targets for drive without I/O seek. It's quite similar like CFQ, but >>>> the dispatch decision is made according to IOPS instead of slice. >>>> >>>> The algorithm is simple. Drive has a service tree, and each task lives in >>>> the tree. The key into the tree is called vios (virtual I/O). Every request >>>> has vios, which is calculated according to its ioprio, request size and so >>>> on. Task's vios is the sum of vios of all requests it dispatches. FIOPS >>>> always selects task with minimum vios in the service tree and let the task >>>> dispatch request. The dispatched request's vios is then added to the task's >>>> vios and the task is repositioned in the sevice tree. >>>> >>>> The series are orgnized as: >>>> Patch 1: separate CFQ's io context management code. FIOPS will use it too. >>>> Patch 2: The core FIOPS. >>>> Patch 3: request read/write vios scale. This demontrates how the vios scale. >>>> >>>> To make the code simple for easy view, some scale code isn't included here, >>>> some not implementated yet. >>>> >>>> TODO: >>>> 1. ioprio support (have patch already) >>>> 2. request size vios scale >>>> 3. cgroup support >>>> 4. tracing support >>>> 5. automatically select default iosched according to QUEUE_FLAG_NONROT. >>>> >>>> Comments and suggestions are welcome! >>> >>> Benchmark results? >> I didn't have data yet. The patches are still in earlier stage, I want >> to focus on the basic idea first. > since you asked, I tested in a 4 socket machine with 12 X25M SSD jbod, > fs is ext4. > > workload percentage change with fiops against cfq > fio_sync_read_4k -2 > fio_mediaplay_64k 0 > fio_mediaplay_128k 0 > fio_mediaplay_rr_64k 0 > fio_sync_read_rr_4k 0 > fio_sync_write_128k 0 > fio_sync_write_64k -1 > fio_sync_write_4k -2 > fio_sync_write_64k_create 0 > fio_sync_write_rr_64k_create 0 > fio_sync_write_128k_create 0 > fio_aio_randread_4k -4 > fio_aio_randread_64k 0 > fio_aio_randwrite_4k 1 > fio_aio_randwrite_64k 0 > fio_aio_randrw_4k -1 > fio_aio_randrw_64k 0 > fio_tpch 9 > fio_tpcc 0 > fio_mmap_randread_4k -1 > fio_mmap_randread_64k 1 > fio_mmap_randread_1k -8 > fio_mmap_randwrite_4k 35 > fio_mmap_randwrite_64k 22 > fio_mmap_randwrite_1k 28 > fio_mmap_randwrite_4k_halfbusy 24 > fio_mmap_randrw_4k 23 > fio_mmap_randrw_64k 4 > fio_mmap_randrw_1k 22 > fio_mmap_randrw_4k_halfbusy 35 > fio_mmap_sync_read_4k 0 > fio_mmap_sync_read_64k -1 > fio_mmap_sync_read_128k -1 > fio_mmap_sync_read_rr_64k 5 > fio_mmap_sync_read_rr_4k 3 > > The fio_mmap_randread_1k has regression against 3.2-rc7, but no > regression against 3.2-rc6 kernel, still checking why. The fiops has > improvement for read/write mixed workload. CFQ is known not good for > read/write mixed workload. > > Thanks, > Shaohua > Hi, Looks promising. :) Anyway what's your configuration for the test? Did you use vios scaling based on IO direction and/or ioprio? Thanks, Namhyung Kim