From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:40643 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752973AbcJETJP (ORCPT ); Wed, 5 Oct 2016 15:09:15 -0400 Date: Wed, 5 Oct 2016 12:08:33 -0700 From: Shaohua Li To: Tejun Heo CC: Paolo Valente , Vivek Goyal , , , Jens Axboe , , , Mark Brown , Linus Walleij , Ulf Hansson Subject: Re: [PATCH V3 00/11] block-throttle: add .high limit Message-ID: <20161005190832.GA99272@anikkar-mbp.local.dhcp.thefacebook.com> References: <20161004172852.GB73678@anikkar-mbp.local.dhcp.thefacebook.com> <20161004185413.GF4205@htj.duckdns.org> <20161004191427.GG4205@htj.duckdns.org> <20161004202754.GJ4205@htj.duckdns.org> <257945FA-6789-4D80-8DA3-AC75640C71AE@unimore.it> <20161005144946.GA26977@htj.duckdns.org> <20161005183052.GA97491@anikkar-mbp.local.dhcp.thefacebook.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" In-Reply-To: <20161005183052.GA97491@anikkar-mbp.local.dhcp.thefacebook.com> Sender: linux-block-owner@vger.kernel.org List-Id: linux-block@vger.kernel.org On Wed, Oct 05, 2016 at 11:30:53AM -0700, Shaohua Li wrote: > On Wed, Oct 05, 2016 at 10:49:46AM -0400, Tejun Heo wrote: > > Hello, Paolo. > > > > On Wed, Oct 05, 2016 at 02:37:00PM +0200, Paolo Valente wrote: > > > In this respect, for your generic, unpredictable scenario to make > > > sense, there must exist at least one real system that meets the > > > requirements of such a scenario. Or, if such a real system does not > > > yet exist, it must be possible to emulate it. If it is impossible to > > > achieve this last goal either, then I miss the usefulness > > > of looking for solutions for such a scenario. > > > > > > That said, let's define the instance(s) of the scenario that you find > > > most representative, and let's test BFQ on it/them. Numbers will give > > > us the answers. For example, what about all or part of the following > > > groups: > > > . one cyclically doing random I/O for some second and then sequential I/O > > > for the next seconds > > > . one doing, say, quasi-sequential I/O in ON/OFF cycles > > > . one starting an application cyclically > > > . one playing back or streaming a movie > > > > > > For each group, we could then measure the time needed to complete each > > > phase of I/O in each cycle, plus the responsiveness in the group > > > starting an application, plus the frame drop in the group streaming > > > the movie. In addition, we can measure the bandwidth/iops enjoyed by > > > each group, plus, of course, the aggregate throughput of the whole > > > system. In particular we could compare results with throttling, BFQ, > > > and CFQ. > > > > > > Then we could write resulting numbers on the stone, and stick to them > > > until something proves them wrong. > > > > > > What do you (or others) think about it? > > > > That sounds great and yeah it's lame that we didn't start with that. > > Shaohua, would it be difficult to compare how bfq performs against > > blk-throttle? > > I had a test of BFQ. I'm using BFQ found at > http://algogroup.unimore.it/people/paolo/disk_sched/sources.php. version is > 4.7.0-v8r3. It's a LSI SSD, queue depth 32. I use default setting. fio script > is: > > [global] > ioengine=libaio > direct=1 > readwrite=randread > bs=4k > runtime=60 > time_based=1 > file_service_type=random:36 > overwrite=1 > thread=0 > group_reporting=1 > filename=/dev/sdb > iodepth=1 > numjobs=8 > > [groupA] > prio=2 > > [groupB] > new_group > prio=6 > > I'll change iodepth, numjobs and prio in different tests. result unit is MB/s. > > iodepth=1 numjobs=1 prio 4:4 > CFQ: 28:28 BFQ: 21:21 deadline: 29:29 > > iodepth=8 numjobs=1 prio 4:4 > CFQ: 162:162 BFQ: 102:98 deadline: 205:205 > > iodepth=1 numjobs=8 prio 4:4 > CFQ: 157:157 BFQ: 81:92 deadline: 196:197 > > iodepth=1 numjobs=1 prio 2:6 > CFQ: 26.7:27.6 BFQ: 20:6 deadline: 29:29 > > iodepth=8 numjobs=1 prio 2:6 > CFQ: 166:174 BFQ: 139:72 deadline: 202:202 > > iodepth=1 numjobs=8 prio 2:6 > CFQ: 148:150 BFQ: 90:77 deadline: 198:197 More tests: iodepth=8 numjobs=1 prio 2:6, group A has 50M/s limit CFQ:51:207 BFQ: 51:45 deadline: 51:216 iodepth=1 numjobs=1 prio 2:6, group A bs=4k, group B bs=64k CFQ:25:249 BFQ: 23:42 deadline: 26:251 Thanks, Shaohua