Re: RFE: Graphing and iteration support for fio

[Jens Axboe <axboe@kernel.dk>]

On 12/01/2015 04:04 AM, Avi Kivity wrote:
> Sometimes you want to run a set of experiments on a disk, varying a
> parameter between tests (in my case, iodepth, but buffer size is also a
> good candidate).  You then want to present the results in a nice graph.
>
> I wrote a small wrapper around fio to do this
> (https://github.com/avikivity/diskplorer), but it occurs to me that
> generalized support for both in fio would be much more useful.
>
> Possibly, you'd define a job as a template:
>
> [aio-read]
> template_start=1
> template_end=100
> template_step=1
> (or template_ratio=1.05 for exponential growth)
> iodepth=template_variable
>
> (it's just possible that someone can come up with better syntax).
>
> A few more options in the global section can then cause a graph to be
> generated.

It'd be great to integrate this into fio, as graphing results is 
something that most people want to do. Any chance you would be willing 
to try and hash that out?

> btw, a fast disk can easily saturate a single core using libaio, so a
> multithreaded libaio ioengine would be welcome (I am currently emulating
> it using multiple jobs and new_group).

In the context of fio, that doesn't make a lot of sense. A job in fio 
is, by definition, either a thread or a process that does IO. So if you 
want more threads banging on a device, then you'd add more jobs. If 
multiple threads shared on aio context, then we'd also potentially see 
contention on that part. If you just use more jobs, then each gets an 
aio context as well.

-- 
Jens Axboe