Why zipf distribution can not be 1.0

Why zipf distribution can not be 1.0

[Yufei Ren]

Hi,

Is the 'zipf theta' the value of the exponent characterizing the zipf
distribution? If so, why could not it be 1.0? With the following job
file, fio sent out an error - fio: zipf theta must different than 1.0.

[job]
ioengine=null
rw=randread
norandommap
size=1280m
bs=4k
random_distribution=zipf:1

I looked through the fio zipf library but was confused with
zipf_next() function? Any illustration about this zipf distribution
generator?

Thanks
Yufei

Re: Why zipf distribution can not be 1.0

[Jens Axboe]

On Sun, Jan 27 2013, Yufei Ren wrote:
> Hi,
> 
> Is the 'zipf theta' the value of the exponent characterizing the zipf
> distribution? If so, why could not it be 1.0? With the following job
> file, fio sent out an error - fio: zipf theta must different than 1.0.
> 
> [job]
> ioengine=null
> rw=randread
> norandommap
> size=1280m
> bs=4k
> random_distribution=zipf:1
> 
> I looked through the fio zipf library but was confused with
> zipf_next() function? Any illustration about this zipf distribution
> generator?

The point is that a theta of 1.0 would be the same as a normal uniform
distrobution. But perhaps it should just be allowed, you should get what
you ask for...

Not sure on your last question. Can you expand on that? If it's on the
zipf distribution in general, google/wikipedia is your friend :-)

-- 
Jens Axboe