On Tue, Apr 24, 2018 at 03:24:55PM +0200, Harald Freudenberger wrote:
> The condition is true and terminates the function
> when the count value of the cpu fast pool is below 64
> AND the time since last mix of the pool is lower than
> HZ (so lower than 1s).
> This means the code following this condition is runu
> when the count value is > 64 or the last mix is more
> than 1s old.
> As the fast_mix() function does a fast_pool->count++
> effectively every 64 invocations this condition is
> false and the rest of the function is executed.
>
> Is this the intention?
Yes, that's the intention. Originally we required sampling the IP
and/or architecture's cycle counter (if available) and mixing it using
fast_mix before we transfer it to the input_pool and credit it with a
bit of entropy.
The problem is that on some architectures interrupts happen are much
less frequently. So what we did is to assume that one second's worth
of interrupts will be sufficient to derive a single bit of entropy.
- Ted
