One of the thread i went though: http://www.spinics.net/lists/fio/msg00876.html does state that using refill_buffers should give fully different random data everytime. Srinivasa R Chamarthy On Thu, May 7, 2015 at 11:58 AM, Srinivasa Chamarthy <chamarthy.raju@xxxxxxxxx> wrote: > Thanks Eaton. One question thought. From the man page for refill_buffers: > > "If this option is given, fio will refill the IO buffers on every > submit. The default is to only fill it at init time and reuse that > data. Only makes sense if zero_buffers isn't specified, naturally. If > data verification is enabled, refill_buffers is also automatically > enabled." > > Every IO submitted will have a new pattern for repeated workloads? > using refill_buffers, i seem to get same pattern repeatedly. Is that > how it should be? i was under the impression that refill will use new > pattern every time. > > # fio --filename=test_refill --readwrite=randwrite --size=1m > --refill_buffers --bs=256k --norandommap --name=refill > # for each in {0..3}; do dd if=test_refill bs=262144 count=1 > skip=$each 2>/dev/null | md5sum; done > 86c3e47e173a58ad93470fd8db856f8c - > 6fe5ce86d04522889c99809d6d97cb94 - > 9113ce00f3781861afc41aaf6da32428 - > f0b575c40e9da23b524f585723cbea4e - > > # fio --filename=test_refill --readwrite=randwrite --size=1m > --refill_buffers --bs=256k --norandommap --name=refill > # for each in {0..3}; do dd if=test_refill bs=262144 count=1 > skip=$each 2>/dev/null | md5sum; done > 86c3e47e173a58ad93470fd8db856f8c - > 6fe5ce86d04522889c99809d6d97cb94 - > 9113ce00f3781861afc41aaf6da32428 - > f0b575c40e9da23b524f585723cbea4e - > Srinivasa R Chamarthy > > > On Thu, May 7, 2015 at 10:19 AM, Matthew Eaton <m.eaton82@xxxxxxxxx> wrote: >> It doesn't make sense to set refill_buffers and scramble_buffers at >> the same time, since you won't get any repeating data with >> refill_buffers set. >> >> On Mon, May 4, 2015 at 7:23 PM, Srinivasa Chamarthy >> <chamarthy.raju@xxxxxxxxx> wrote: >>> Thanks Jens. I was using refill_buffers and scramble_buffers at the >>> same time. If i specify them at the same time, there seems to be no >>> difference in the workloads. If i specify scramble_buffers then there >>> shouldn't be refill_buffers specified to get the buffers differently. >>> Thanks. >>> Srinivasa R Chamarthy >>> >>> >>> On Tue, May 5, 2015 at 4:39 AM, Jens Axboe <axboe@xxxxxxxxx> wrote: >>>> On 04/25/2015 07:03 AM, Srinivasa Chamarthy wrote: >>>>> >>>>> Firstly, thanks before in hand. :) >>>>> >>>>> Using FIO, what is the way to achieve a work load with specific number >>>>> of unique blocks duplicates for specific number of times. For Example, >>>>> i want a 252k block duplicates 1000 times and i want it to be the >>>>> unique block in the complete workload. >>>> >>>> >>>> If you have very specific requirements, it might be easier to simply write >>>> an iolog generator that spits out what you want the pattern to look like. >>>> Then fio can import that, and run the workload. >>>> >>>>> Another query is that, for a blocksize of 256k does the io buffers are >>>>> created at 256k and written to the disk and are all those 256k blocks >>>>> unique buffer?. Can there be a change that in a 256k block, the >>>>> smaller size buffers be the same? >>>> >>>> >>>> That depends on the settings for compressibility, dedupability, etc. In >>>> general see scramble_buffers, refill_buffers, and so on. That is all in the >>>> man page or HOWTO. >>>> >>>> -- >>>> 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 -- 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
