I agree that changing the zoned random distribution parameter to allow absolute sizes would be an elegant way to address my use case. I'm not sure if it would be easier to add that functionality to the zoned distribution or create a new distribution named something like zoned_sectors. I'd also like the ability to have zones that no I/O will fall into. I think the easiest way to do that would be to allow 0 as a valid distribution percentage (I.E. something like random_distribution=zoned:10/10:0/50:30/20:8/30:2/40). Currently it seems I can specify 0 as a distribution percentage, but it doesn't create a zero I/O zone like I would like it to. Although that might be addressed just by making the zoned distribution randomize I/O as expected. Thanks for looking into this, Phillip Chen On Mon, Nov 20, 2017 at 6:57 PM, Jens Axboe <axboe@xxxxxxxxx> wrote: > On 11/20/2017 10:17 AM, Phillip Chen wrote: >> Hello, >> I'm a test engineer at Seagate and we're using FIO to gather some >> performance data. This email has two parts: a bug report and a feature >> request. >> The bug that I'm seeing is that when using the >> random_distribution=zoned argument, the zone order is not honored. So >> using zoned:18/90:7/5:75/5 will not weight IO towards the end of the >> disk but rather towards the beginning. Using zoned:75/5:7/5:18/90 >> apparently gives the same distribution, but also not the correct >> distribution. I've attached a python3.6 script that shows this >> behaviour. Here is the histogram information from running the two >> zoned arguments as described above: >> >> Using fio --name=rand_reads --ioengine=libaio --direct=1 --exitall >> --thread --filename=/dev/sdc --runtime=30 --readwrite=randread >> --iodepth=1 --random_distribution=zoned:18/90:7/5:75/5 --norandommap >> --output-format=terse >> histogram bins = [2302, 25, 25, 30, 33, 36, 26, 32, 29, 37, 21, 21, >> 32, 27, 49, 34, 24, 36, 26, 184] >> histogram percents = [75.99867943215582, 0.8253549026081215, >> 0.8253549026081215, 0.9904258831297458, 1.0894684714427203, >> 1.188511059755695, 0.8583690987124464, 1.0564542753383954, >> 0.9574116870254209, 1.2215252558600198, 0.6932981181908221, >> 0.6932981181908221, 1.0564542753383954, 0.8913832948167713, >> 1.6176956091119181, 1.1224826675470452, 0.7923407065037966, >> 1.188511059755695, 0.8583690987124464, 6.074612083195774] >> >> Using fio --name=rand_reads --ioengine=libaio --direct=1 --exitall >> --thread --filename=/dev/sdc --runtime=30 --readwrite=randread >> --iodepth=1 --random_distribu tion=zoned:75/5:7/5:18/90 >> --norandommap --output-format=terse >> histogram bins = [2306, 25, 25, 30, 33, 36, 26, 32, 29, 37, 21, 21, >> 32, 27, 49, 34, 24, 36, 26, 184] >> histogram percents = [76.03033300362677, 0.8242664029014177, >> 0.8242664029014177, 0.9891196834817013, 1.0880316518298714, >> 1.1869436201780414, 0.8572370590174745, 1.0550609957138146, >> 0.9561490273656446, 1.2199142762940982, 0.6923837784371909, >> 0.6923837784371909, 1.0550609957138146, 0.8902077151335311, >> 1.6155621496867787, 1.1210023079459281, 0.7912957467853611, >> 1.1869436201780414, 0.8572370590174745, 6.0666007253544345] >> >> To run the script, use the -h flag to see usage, but at a minimum >> you'll need to give the device handle to run on as the first argument >> (the workload only does reads). The random_distribution argument is >> set at the top of the file. > > I'll take a look at this tomorrow, that does seem very fishy. > >> Here is my environment information: >> # cat /etc/centos-release >> CentOS Linux release 7.3.1611 (Core) >> # uname -r >> 3.10.0-514.21.1.el7.x86_64 >> I used fio-3.2-13-g40e5f which was the newest version I could see as of today. >> >> As for the feature request: >> I am trying to adapt our current FIO job files for FLEX testing which >> is a new protocol we announced recently >> (http://blog.seagate.com/intelligent/new-flex-dynamic-recording-method-redefines-data-center-hard-drive/) >> that has some requirements on where writes/reads are allowed. I would >> like to have better control where random reads and writes are going >> using the zoned random_distribution setting using sector numbers >> rather than capacity percentages. Would that be a possible feature to >> add? Or is there an existing way to randomly read/write to >> non-contiguous zones on the disk with varying sizes? > > The best way to request something like that is to come up with a logical > way to describe it. That's usually the hardest part, implementing it is > usually not that hard. This is especially important since it has to be > intuitively easy to use for the user, not requiring them to pour too > much over man pages. > > For yours, the zoned setup already supports split ranges for > reads/writes/trims. The change seems to be that you want to give the > zones in absolute sizes instead. It'd be the easiest to extend the > zoning to allow sizes instead. > > -- > Jens Axboe > -- To unsubscribe from this list: send the line "unsubscribe fio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
