Re: [PATCH] (0/4) Entropy accounting fixes

From: Linus Torvalds (
Date: Sat Aug 17 2002 - 22:08:36 EST

On Sat, 17 Aug 2002, Oliver Xymoron wrote:
> Let me clarify that 2-5 orders thing. The kernel trusts about 10 times
> as many samples as it should, and overestimates each samples' entropy
> by about a factor of 10 (on x86 with TSC) or 1.3 (using 1kHz jiffies).

Lookin gat the code, your _new_ code just throws samples away _entirely_
just because some random event hasn't happened (the first thing I noticed
was the context switch testing, there may be others there that I just
didn't react to).

In short, you seem to cut those random events to _zero_. And this happens
under what seems to be perfectly realistic loads. That's not trying to fix
things, that's just breaking them.

> The patches will be a nuisance for anyone who's currently using
> /dev/random to generate session keys on busy SSL servers.

No, it appears to be a nuisanse even for people who have real issues, ie
just generating _occasional_ numbers on machines that just don't happen to
run much user space programs.


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