rand_harvestq high cpu usage when /dev/urandom is used

[Danilo Egêa Gondolfo]

On Mon, Aug 20, 2018 at 8:54 AM Mark Millard via freebsd-hackers <
freebsd-hackers at freebsd.org> wrote:

>
>
> On 2018-Aug-20, at 4:27 AM, Ali Abdallah <aliovx at gmail.com> wrote:
>
> > . . .
> > Also, I read on
> >
> https://lists.freebsd.org/pipermail/freebsd-current/2013-November/046683.html
> > someone saying that sysctls to turn off harvesting is documented in
> > random(6)
>
>
> It says random(4), so:
>
> <
> https://www.freebsd.org/cgi/man.cgi?query=random&sektion=4&manpath=freebsd-release-ports
> >.
>
> > . . .
>
> ===
> Mark Millard
> marklmi at yahoo.com
> ( dsl-only.net went
> away in early 2018-Mar)
>
> _______________________________________________
> freebsd-hackers at freebsd.org mailing list
> https://lists.freebsd.org/mailman/listinfo/freebsd-hackers
> To unsubscribe, send any mail to "freebsd-hackers-unsubscribe at freebsd.org"
>

 I can confirm this is happening.

It's easily reproducible: dd if=/dev/urandom of=/dev/null
rand_harvestq eat 100% of one CPU for minutes, in my case the system became
unresponsive (it freezes for few seconds).

I'm running FreeBSD 12.0-ALPHA2 #14 r337973M



-- 
Danilo.
@daniloegea
http://people.freebsd.org/~danilo/