Re: nacl and CPU frequency.
On Sat, Sep 22, 2012 at 05:29:45PM +0100, peter green wrote:
> I therefore conclude that if it's not returning elapsed times in true CPU
> cycles it probablly doesn't matter much if the supposed CPU speed and the
> real CPU speed are not exactly the same.
>
> As such unless someone objects I plan to patch the code to fallback to
> using bogomips as a "psuedo CPU speed" if true CPU speed cannot be
> determined.
procps has been struggling with this for years, though ita mainly around
the CPU ticks versus real seconds. If you are really bored, have a look
at some old procps bugs where this sort of thing has broken.
We've narrowed it down to a small handful of checks. The real value is
probably unknown for some devices so we just set it to a fixed value.
The point is, trying to guess this sort of stuff will probably give you
the wrong number so a "pseduo CPU speed" is probably as bad as anything
else you can come up with, so find something simple.
- Craig
--
Craig Small VK2XLZ http://enc.com.au/ csmall at : enc.com.au
Debian GNU/Linux http://www.debian.org/ csmall at : debian.org
GPG fingerprint: 5D2F B320 B825 D939 04D2 0519 3938 F96B DF50 FEA5
Reply to: