Bug#722898: benchmarks

[Thiemo Nagel <thiemo.nagel@gmail.com>]

Hello Gaudenz,

thank you for your email!

Any reason why you choose 512k? If I understand your benchmarks right,
doubling this to 1M yelds about another 27% gain.

I'm sorry, I forgot to mention that I've re-run the benchmarks. After removing O_SYNC, the performance was identical for block sizes in the range of 32k to 16M. I chose 512k (16 times larger than the lowest value that I've tested) with the intent to exclude a block size penalty for devices up to 16x faster than my md raid1 setup, which comes in at around 80MB/s.

Except for low-memory installs, I'm not aware of any obstacle to increasing the buffer even more. (And of course, there's always the option to test for available memory and chose the buffer size depending on that.)

 

> #2    blockdev-wipe: Reduce progress indicator granularity to 1/1000

This still sounds like a lot of granularity. IMO this could be reduced
to 1/100. Do we really need progress updates for less than 1%?

For a large device, wipe times still can be many hours. At a granularity of 1/1000, the progress indicator would advance every 10-50 seconds (order of magnitude), which I don't consider excessive. (Of course, this only holds true if the graphical frontend supports this kind of granularity, which I don't know.)

Cheers,
Thiemo