Yes that is correct.
So e.g. if you have RND_RD b/w 45MBps and had 10%SEQ_WR 90%RND_RD the
write throughput will be:
=10/100 *45MBs = ~4.5MB/s
Now if you try to cap the write throughput (rate =5m) to this in
Linux, the RND_RD also gets impacted and wont run to its full
potential.
In StorScor reads thread will not get capped and only writes thread
will be capped, hence deliver the expected results.
On Thu, Jul 13, 2017 at 1:33 PM, Sitsofe Wheeler <sitsofe@xxxxxxxxx> wrote:
> Hey,
>
> My Perl is a bit rusty but look at how the write throughput is calculated:
>
> # Run again, this time with an aggressor process injecting
> # writes in the background. The aggressor is rate-limited
> # to a fraction of the baseline read throughput.
> foreach my $write_workload ( @write_workloads )
> {
> my ($write_pattern, $write_pct) = @$write_workload;
>
> my $write_tput_KBps =
> int ( ( $write_pct / 100 ) * $read_tput_KBps );
>
> So it is accounting for the fact that the write throughput will be
> limited to a percentage of the read throughput.
>
> On 13 July 2017 at 20:02, abhishek koundal <akoundal@xxxxxxxxx> wrote:
>> Hi,
>> The main thing that i am trying to do is to model the storScor in
>> linux enviornment
>> (https://github.com/Microsoft/StorScore/blob/master/recipes/write_impact_check.rcp).
>> So there you can control the rate of the of the writes as per the %
>> that is required. While running that on windows i can see that i can
>> have different BS and rate defined for the runs achieving expected
>> output.
>>
>> In the above mentioned case the RND_RD will be unconstrained (i.e.
>> full BW they can achieve) but writes will be slowed to x% of RND_RD.
>> In fio when
>> e.g.
>> SEQ_WR 10% and RND_RD 90%, with seq_wr rate capped at 10% of rnd rd
>> (if rnd_rd was 40m)
>> [SEQ_WR]
>> rate=4m
>> bs=128K
>> rw=write
>> flow=9
>> [RND_RD]
>> rate=40m
>> bs=4k
>> rw=randread
>> flow=-1
>> When i run this the output that comes back shows that SEQ_WR b/w is
>> capped ~ 4m but RND_RD also gets severely hit for the IOPS+BW as it
>> tried to put the total BW under <45m>. I want that RND_RD doesn't need
>> to be capped and should run to it closest potential like I am see in
>> storScor.
>> Really appreciate for the support and helping me understand the limitations.
>
> --
> Sitsofe | http://sucs.org/~sits/
--
Life is too short for silly things so invest your time in some
productive outputs!!
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