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

From: Oliver Xymoron (
Date: Sat Aug 17 2002 - 23:30:16 EST

On Sat, Aug 17, 2002 at 08:08:36PM -0700, Linus Torvalds wrote:
> 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).

No, it still mixes them in.
> 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.

Read the code again. Better yet, try it.

23:06ash~$ cat /proc/sys/kernel/random/entropy_avail
23:17ash~$ w
 23:17:22 up 11 min, 2 users, load average: 0.09, 0.06, 0.05

It was probably full in less than 11 minutes.

 "Love the dolphins," she advised him. "Write by W.A.S.T.E.." 
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