Re: [PATCH,RFC] random: collect cpu randomness

From: JÃrn Engel
Date: Sun Feb 02 2014 - 22:34:57 EST

On Sun, 2 February 2014 20:39:22 -0500, Theodore Ts'o wrote:
> The real question is how much overhead does it add, and is it worth
> it. JÃrn, I take it that was the reason for creating an even faster,
> but weaker mixing function? Was the existing "fast mix" causing a
> measurable overhead, or was this your just being really paranoid about
> not adding anything to the various kernel fastpaths?

It was paranoia. And I am still somewhat paranoid and don't trust my
benchmark results yet. Maybe on an 1024-CPU Altix with a 100k-thread
workload the overhead is too much. Just because I couldn't measure a
difference on my wimpy notebook does not mean much.


One of the painful things about our time is that those who feel certainty
are stupid, and those with any imagination and understanding are filled
with doubt and indecision.
-- Bertrand Russell
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