Re: FIO achieves only 50:50 of read:write IOPS when rwmix is not 50:50 and achieves only about 40% of total IOPS

[GV Govindasamy <gv.govindasamy@xxxxxxxxxxx>]

Thanks Sitsofe. After removing “rate_process=poisson” and giving “rate=<in-bytes>”, I can see the IOPS I have calculated for. In this case, 90 read ops and 10 write ops.

“rate_process=poisson” is a bug in this case then?

Thanks
+GV

=============================
[global]
ioengine=libaio
direct=1
time_based
norandommap
group_reporting
disk_util=0
continue_on_error=all
;rate_process=poisson

[db-oltp-w]
bssplit=8k/90:16k/10
;bs=8k
size=128G
filename=/dev/sdg
rw=randrw
iodepth=8
rwmixread=90
rwmixwrite=10
write_iolog=rwmix.csv
;rate_iops=90,10,
rate=811008,90112,
===============================

On 4/5/17, 3:46 PM, "Sitsofe Wheeler" <sitsofe@xxxxxxxxx> wrote:

    Hi,
    
    On 5 April 2017 at 17:25, GV Govindasamy <gv.govindasamy@xxxxxxxxxxx> wrote:
    >
    > In the following example, I would like 90 read ops and 10 write ops. Regardless of the values in "bssplit" or "bs" and "rwmixread/rwmixwrite" values, not able to see FIO doing 90:10 read:writes and total ops turns out to be ~20+~20 = ~40 IOPS instead of 100.
    >
    > Am I missing something here?
    >
    > Thanks
    > +GV
    >
    > =============================================
    > $ ./fio-2.19 --version (compiled with: ./configure --build-static; make on CentOS release 6.7/3.10.0-229)
    > fio-2.19
    >
    > ==========================
    > $ cat output/fio/bssplit_rwmix.fio
    > [global]
    > ioengine=libaio
    > direct=1
    > time_based
    > norandommap
    > group_reporting
    > disk_util=0
    > continue_on_error=all
    > rate_process=poisson
    >
    > [db-oltp-w]
    > bssplit=8k/90:16k/10
    > size=128G
    > filename=/dev/sdg
    > rw=randrw
    > iodepth=8
    > rwmixread=90
    > rwmixwrite=10
    > rate_iops=90,10,0
    
    I think the problem may lie with rate_process=poisson - if you remove
    that does the workload perform better? Perhaps it is not treating the
    read and write rates independently...
    
    -- 
    Sitsofe | http://sucs.org/~sits/
    

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