Libguestfs - Apr 2022 - nbdkit: determining block size distribution

Hello,

I want to find out the request size distribution of NBD read, write, and trim
requests for a given workload. Background is that I want to figure out the ideal
block size for the backing storage used my an nbdkit plugin.

It seems to me that the best way to get this information would be to write an
appropriate nbdkit filter, but I was surprised that the stats filter output is
rather rudimentary.

Would patches be accepted to add block size histograms? Or is there a better way
to do this?

Best,
-Nikolaus

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On Sun, Apr 24, 2022 at 06:44:04PM +0100, Nikolaus Rath
wrote:
> Hello,
>
> I want to find out the request size distribution of NBD read, write,
> and trim requests for a given workload. Background is that I want to
> figure out the ideal block size for the backing storage used my an
> nbdkit plugin.
>
> It seems to me that the best way to get this information would be to
> write an appropriate nbdkit filter, but I was surprised that the
> stats filter output is rather rudimentary.
>
> Would patches be accepted to add block size histograms? Or is there
> a better way to do this?
Sounds like a good idea to extend the stats filter.  It already prints
some summary lines, so it could print a histogram of block sizes
encountered too.

Rich.

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