On 29 March 2018 at 08:28, Michael Green <mishagreen@xxxxxxxxx> wrote: > >> On Mar 21, 2018, at 7:34 AM, Jens Axboe <axboe@xxxxxxxxx> wrote: >> >> On 3/16/18 12:45 PM, Jeff Furlong wrote: >>> A few comments: >>> >>> -How does the cpu utilization look compared between the lfsr and >>> default tausworthe generators? Is the cpu util actually higher on >>> lfsr? If it is near saturated on 16 devices, then naturally >>> throughput would decrease. >> >> The LFSR generator is constant overhead, and it should not degrade as >> more jobs are using it. There's no shared state at all. > > Actually it’s only one job. In this case we mean "fio jobs" (rather than fio invocations). From the line in one of your other emails: fio --name=global --thread=1 --direct=1 --group_reporting=1 --name=PT7 --rw=randrw --rwmixread=100 --iodepth=40 --numjobs=8 --bs=4096 --runtime=120 --filename='/dev/e8b0:/dev/e8b1:/dev/e8b2:/dev/e8b3:/dev/e8b4:/dev/e8b5:/dev/e8b6:/dev/e8b7:/dev/e8b8:/dev/e8b9:/dev/e8b10:/dev/e8b11:/dev/e8b12:/dev/e8b13:/dev/e8b14:/dev/e8b15' --ioengine=libaio --random_generator=lfsr You have --numjobs=8 (http://fio.readthedocs.io/en/latest/fio_doc.html#cmdoption-arg-numjobs ) there so you are spawning 8 fio internal jobs which all work on those same files simultaneously. -- 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
