Re: [Tails-dev] performance test: randomsound vs haveged

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Autor: adrelanos
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Para: The Tails public development discussion list
Assunto: Re: [Tails-dev] performance test: randomsound vs haveged
> adrelanos@??? wrote (18 Dec 2012 22:18:28 GMT) :
>>> Hi,
>>>
>>> adrelanos wrote (16 Dec 2012 18:19:44 GMT) :
>>>> - Do they block each other or result in even more entropy available?
>>>> [...]
>>>> haveged only                     ~1100 and ~4000
>>>> randomsound and haveged             ~1100 and ~4000

>>>
>>> Isn't this capped by /proc/sys/kernel/random/poolsize ?
>
>> No.
>> https://www.kernel.org/doc/man-pages/online/pages/man4/random.4.html
>
> Thanks.
>
>        The read-only file entropy_avail gives the available entropy.
>        Normally, this will be 4096 (bits), a full entropy pool.

>
>        The file poolsize gives the size of the entropy pool.
>        The semantics of this file vary across kernel versions:
>        [...]
>               Linux 2.6:  This file is read-only, and gives the size of
> the entropy
>                           pool in bits. It contains the value 4096.

>
> I admit I've not checked the code, but in my understanding of this
> documentation, it confirms the available entropy is capped by the
> entropy pool size.


cat /proc/sys/kernel/random/poolsize is always 4096. Unusable for
benchmarking.

cat /proc/sys/kernel/random/entropy_avail numbers always change. Depends
on hardware (real or virtual). Also depending on which entropy related
packages are installed they change even more.

I didn't check the kernel sources either, but this is backed up by
practical tests and instructions on how to benchmark it everywhere. There
is a consensus.

http://manyrootsofallevilrants.blogspot.co.at/2011/06/rng-utils-and-entropy-rhel6-style.html
http://pthree.org/2012/09/14/haveged-a-true-random-number-generator/