[mythtv-users] What is a "dual core processor"?

ryan patterson ryan.goat at gmail.com
Fri Dec 5 13:31:13 UTC 2008


On Thu, Dec 4, 2008 at 4:08 PM, David Brodbeck <gull at gull.us> wrote:
> ryan patterson wrote:
>> Furthermore hyperthreading is not a gimmick like you are saying.
>> Hyperthreading is very useful in systems that spend a lot of time near
>> 100% CPU usage.
>
> That isn't my experience.
>
> For example, on a Pentium 4 system I was using as a VPN endpoint, I
> benchmarked the transfer rate both with and without hyperthreading.  The
> limiting factor on this machine was the CPU power needed to encrypt the
> data.  I found openvpn could achieve higher transfer rates without
> hyperthreading than with.  It wasn't a small difference, either, on the
> order of 10-15%.
>
> I'm sure there are situations where hyperthreading works, or Intel
> wouldn't have released it, but they seem to be rare in the Linux world.
>  Maybe it's different if you use Intel's optimizing compiler instead of gcc.
>

Your single VPN encryption thread does not place enough of a load on
your CPU to benefit from hyperthreading.  For example if you have a
dual core HT CPU you need 3 or more independent threads, that all want
100% CPU usage at the same time for an extended period of time, to see
hyperthreading work.

Hyperthreading was not designed for or marketed towards the home user.

-- 
_____________
Ryan Patterson


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