From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Subject: Re: Specify range and distribution of accesses References: <20160303161828.GC22164@kernel.dk> <20160303200446.GA2234@kernel.dk> From: Jens Axboe Message-ID: <56DE3BC2.6040206@kernel.dk> Date: Mon, 7 Mar 2016 19:41:06 -0700 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit To: Andrey Kuzmin , Jeff Furlong Cc: "fio@vger.kernel.org" List-ID: On 03/07/2016 02:02 PM, Andrey Kuzmin wrote: > On Mon, Mar 7, 2016 at 11:46 PM, Jeff Furlong wrote: >> Thanks for the suggestions and patches. Using the latest fio version, the JESD219 workload is possible: > > Nice. > >> >> # fio -version >> fio-2.6-27-gd283 >> >> # fio --name=JESD219 --ioengine=libaio --direct=1 --rw=randrw --norandommap --randrepeat=0 --rwmixread=40 --rwmixwrite=60 --iodepth=256 --size=100% --numjobs=4 --bssplit=512/4:1024/1:1536/1:2048/1:2560/1:3072/1:3584/1:4k/67:8k/10:16k/7:32k/3:64k/3 --random_distribution=zoned:50/5:30/15:20/80 --overwrite=1 --filename=/dev/nvme0n1 --group_reporting --runtime=5m --time_based --output=JESD219 >> >> A quick statistical analysis of the results shows: >> >> Found 20380582 IOs >> >> Found 39.9903152913% reads >> Found 60.0096847087% writes >> >> Found 4.00492979052% 512 >> Found 1.00495658073% 1024 >> Found 1.00079575745% 1536 >> Found 1.00046701316% 2048 >> Found 0.998764412125% 2560 >> Found 0.998043137335% 3072 >> Found 0.999520033334% 3584 >> Found 67.0145778958% 4096 >> Found 9.98662844859% 8192 >> Found 6.99898560306% 16384 >> Found 2.99961993235% 32768 >> Found 2.99271139558% 65536 >> >> Found 49.9895734086% 0-5% >> Found 30.0126463513% 5-20%% >> Found 19.99778024% 20-100% >> > > It hardly matters, but is still somewhat surprising to see that both > bs and zone split percentage are accurate only up to 5x10^-3. So I did the math on these, an fio is on (or really close) to the expected deviation for random outcomes. The first two of the block sizes (didn't check more): > Found 4.00492979052% 512 3.99387% to 4.00612% would be in the range. > Found 1.00495658073% 1024 0.9938778% to 1.00612% would be in the range. For the access location: > Found 49.9895734086% 0-5% 49.98955% to 50.01044% would be in the range. > Found 30.0126463513% 5-20%% 29.98955% to 30.01044% would be in the range. > Found 19.99778024% 20-100% 19.98955% to 20.01044% would be in the range. So while the deviations from the specified does seem larger than intuition would lead you to believe, it's actually really close. I think we can call this one closed. -- Jens Axboe