Question: can anyone tell me what QD exactly a device is received from this test script

Question: can anyone tell me what QD exactly a device is received from this test script

[Jing Booth]

Hi all,

In the test script shown below, it has [global] section and [nvme0n1] section. The test script is used to test a storage device. What queue depth does the storage device receive? Thanks

fio --name=global --ba=16K --bs=16K --buffered=0 --ioengine=libaio --nice=-10 --rw=randrw --size=100% --status-interval=1 --ramp_time=2 --runtime=5 --time_based --rwmixread=25 --group_reporting --numjobs=4 --iodepth=16 --norandommap --random_generator=tausworthe64 --randrepeat=0 --percentile_list=99:99.9:99.99:99.999:99.9999:99.99999:99.999999:99.9999999 --name=nvme0n1 --filename=/dev/nvme0n1  --iodepth=64

Re: Question: can anyone tell me what QD exactly a device is received from this test script

[Sitsofe Wheeler]

Hi,

On Fri, 22 Feb 2019 at 16:19, Jing Booth <Jing.Booth@wdc.com> wrote:
>
> Hi all,
>
> In the test script shown below, it has [global] section and [nvme0n1] section. The test script is used to test a storage device. What queue depth does the storage device receive? Thanks
>
> fio --name=global --ba=16K --bs=16K --buffered=0 --ioengine=libaio --nice=-10 --rw=randrw --size=100% --status-interval=1 --ramp_time=2 --runtime=5 --time_based --rwmixread=25 --group_reporting --numjobs=4 --iodepth=16 --norandommap --random_generator=tausworthe64 --randrepeat=0 --percentile_list=99:99.9:99.99:99.999:99.9999:99.99999:99.999999:99.9999999 --name=nvme0n1 --filename=/dev/nvme0n1  --iodepth=64

Something like 4 if you count all jobs together (because numjobs is 4)
but you can check for yourself by looking at the submit line in the IO
depths output that fio produces.

Did you see the warnings with the libaio engine in the
manual/documentation
(https://fio.readthedocs.io/en/latest/fio_doc.html#i-o-engine ) or the
warning in the iodepth option section
(https://fio.readthedocs.io/en/latest/fio_doc.html#cmdoption-arg-iodepth
)?

-- 
Sitsofe | http://sucs.org/~sits/

Re: Question: can anyone tell me what QD exactly a device is received from this test script

[Jeff Moyer]

Sitsofe Wheeler <sitsofe@gmail.com> writes:

> Hi,
>
> On Fri, 22 Feb 2019 at 16:19, Jing Booth <Jing.Booth@wdc.com> wrote:
>>
>> Hi all,
>>
>> In the test script shown below, it has [global] section and
>> [nvme0n1] section. The test script is used to test a storage
>> device. What queue depth does the storage device receive? Thanks
>>
>> fio --name=global --ba=16K --bs=16K --buffered=0 --ioengine=libaio
>> --nice=-10 --rw=randrw --size=100% --status-interval=1 --ramp_time=2
>> --runtime=5 --time_based --rwmixread=25 --group_reporting
>> --numjobs=4 --iodepth=16 --norandommap
>> --random_generator=tausworthe64 --randrepeat=0
>> --percentile_list=99:99.9:99.99:99.999:99.9999:99.99999:99.999999:99.9999999
>> --name=nvme0n1 --filename=/dev/nvme0n1 --iodepth=64
>
> Something like 4 if you count all jobs together (because numjobs is 4)
> but you can check for yourself by looking at the submit line in the IO
> depths output that fio produces.
>
> Did you see the warnings with the libaio engine in the
> manual/documentation
> (https://fio.readthedocs.io/en/latest/fio_doc.html#i-o-engine ) or the
> warning in the iodepth option section
> (https://fio.readthedocs.io/en/latest/fio_doc.html#cmdoption-arg-iodepth
> )?

He specified buffered=0.  The end result will by 64 * 4 = 256.  Of
course, at the device things may differ due to splitting and/or merging
of I/O in the kernel.

Cheers,
Jeff

Re: Question: can anyone tell me what QD exactly a device is received from this test script

[Sitsofe Wheeler]

On Fri, 22 Feb 2019 at 22:33, Jeff Moyer <jmoyer@redhat.com> wrote:
>
> Sitsofe Wheeler <sitsofe@gmail.com> writes:
>
> > Hi,
> >
> > On Fri, 22 Feb 2019 at 16:19, Jing Booth <Jing.Booth@wdc.com> wrote:
> >>
> >> Hi all,
> >>
> >> In the test script shown below, it has [global] section and
> >> [nvme0n1] section. The test script is used to test a storage
> >> device. What queue depth does the storage device receive? Thanks
> >>
> >> fio --name=global --ba=16K --bs=16K --buffered=0 --ioengine=libaio
> >> --nice=-10 --rw=randrw --size=100% --status-interval=1 --ramp_time=2
> >> --runtime=5 --time_based --rwmixread=25 --group_reporting
> >> --numjobs=4 --iodepth=16 --norandommap
> >> --random_generator=tausworthe64 --randrepeat=0
> >> --percentile_list=99:99.9:99.99:99.999:99.9999:99.99999:99.999999:99.9999999
> >> --name=nvme0n1 --filename=/dev/nvme0n1 --iodepth=64
> >
> > Something like 4 if you count all jobs together (because numjobs is 4)
> > but you can check for yourself by looking at the submit line in the IO
> > depths output that fio produces.
> >
> > Did you see the warnings with the libaio engine in the
> > manual/documentation
> > (https://fio.readthedocs.io/en/latest/fio_doc.html#i-o-engine ) or the
> > warning in the iodepth option section
> > (https://fio.readthedocs.io/en/latest/fio_doc.html#cmdoption-arg-iodepth
> > )?
>
> He specified buffered=0.  The end result will by 64 * 4 = 256.  Of
> course, at the device things may differ due to splitting and/or merging
> of I/O in the kernel.

I stand corrected (I did a quick search for direct=1 in the line
posted and missed buffered=0), thanks Jeff!

I would still recommend looking at what fio reports back and you can
also use external tools like iostat to see what the lower level are
reporting too.

-- 
Sitsofe | http://sucs.org/~sits/