An example of an engine that can't deduce a size by itself is the null engine. Most file based engines (e.g. pvsync, sync, libaio) are able to. I'd really have to see the exact jobs that were run (i.e. the complete command line and fio job file if there was one) and the exact output that you mention showed the problem to say more. For example you say 2TBytes but that's probably not granular enough. What is more interesting is the size of the disk in bytes (from Linux's perspective) because I'd need to know exactly what rounding occured to understand what happened. On 6 March 2018 at 20:28, abhishek koundal <akoundal@xxxxxxxxx> wrote: > Sitsofe > The engine used is the libaio. I hope this helps. > Can you elaborate on the ioengine part which are able to query the > file/disk size and which wont be able to ? (I generally use libaio for > QD>1) > > On Tue, Mar 6, 2018 at 11:47 AM, abhishek koundal <akoundal@xxxxxxxxx> wrote: >> Hi, >> The workload I used was SEQ_MX 70/30 BS 128 QD 128 >> FIO used 3.1 >> Drive SKU = 2TB >> >> On Tue, Mar 6, 2018 at 11:43 AM, abhishek koundal <akoundal@xxxxxxxxx> wrote: >>> Hi, >>> The workload I used was SEQ_MX 70/30 BS 128 QD 128 >>> FIO used 3.1 >>> >>> On Tue, Mar 6, 2018 at 11:11 AM, Sitsofe Wheeler <sitsofe@xxxxxxxxx> wrote: >>>> >>>> On 6 March 2018 at 19:02, Sitsofe Wheeler <sitsofe@xxxxxxxxx> wrote: >>>> > Hi, >>>> > >>>> > On 6 March 2018 at 18:52, abhishek koundal <akoundal@xxxxxxxxx> wrote: >>>> >> All >>>> >> If the size parameter is not given for the runs, how does the tool >>>> >> decide what % (LBA span) needs to be written on the drive? >>>> > >>>> > It will query the disk/file for its size (but this depends on the >>>> > ioengine being able to do that and not all do/can). >>>> > >>>> >> Reason I am asking as I see different data for the same workloads when >>>> >> size=100% and no size parameter used. >>>> > >>>> > Hmm this sounds like it might be due to a rounding issue - what size >>>> > is your disk and what job were you running? >>>> >>>> https://github.com/axboe/fio/blob/master/filesetup.c#L1039-L1048 shows >>>> that when in setup_files() using a size set in percent will round the >>>> io_size down to the minimum block size whereas not setting size at all >>>> looks like it will pass the determined size straight through >>>> unrounded. I'm not sure what job you would see the difference on - >>>> perhaps one that did backwards I/O? -- Sitsofe | http://sucs.org/~sits/ -- 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
