dd test discussion (was Re: possible regression?)

Mulyadi Santosa mulyadi.santosa at gmail.com
Sat Jan 22 12:41:51 EST 2011

Hi again :)

On Sat, Jan 22, 2011 at 19:00, Henry Gebhardt
<hsggebhardt at googlemail.com> wrote:
> The highest I get is 8.5 GB/s with bs=22528 on 2.6.37.

Thanks for sharing your script. Looking at the gnuplot output (again,
thanks for the gnuplot quick hint :) ), I saw it is capped around 7.26
GiB/s, with block size around 300,000-400,000 (that means 293 - 391
KiB, right?)

It's 2.6.36 btw...

I think major factor that involve here, but not limited to them, are:
- L1/L2/L3 cache size
- slab allocator we use
- current memory fragmentation level
- read ahead size


Mulyadi Santosa
Freelance Linux trainer and consultant

blog: the-hydra.blogspot.com
training: mulyaditraining.blogspot.com

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