Re: PAE or not PAE?
- Date: Mon, 12 Mar 2018 19:15:07 -0400
- From: Gene Heskett <gheskett@xxxxxxxxxxx>
- Subject: Re: PAE or not PAE?
On Monday 12 March 2018 15:27:23 Hans wrote:
> > Note that the non PAE kernel in older Debian versions up to Jessie
> > lacked multi-processor (including multi-core and hyper-threading)
> > support.
> Yes, I read this, too. The N280 is a single core, but mith
> hyperthreading, I have two cores.
> Is this still so, that the non-pae-kernel lacks still hyperthreading,
> or does it do today, too?
> And second question: Is PAE preferred (with the look to speed) or
> better use non-pae?
Both pae and hyperthreading take time, hyperthreading quite a bit more
than pae. With hyperthreading, to switch to the 2nd task, takes a
complete processor state stored on the stack, the stack pointer reloaded
to point at the image of the 2nd task, then pull the full register dump
for task 2 back into the processor. Then and only then can the first
cycle devoted to task 2 be initiated. Ditto to swap back. For boxes that
will run a realtime task, the first thing we do is turn off the
hyperthreading. Its a solution that works ok, but I can't think of a
better way to make a decently fast cpu into a provable slowpoke. All it
really does for us is to help heat the shop. You can keep it above the
dew point with electric heat to help control rust, or you can enable
hyperthreading and its exactly the same turns of the electric meter
either way. An excellent demo of the TANSTAAFL principle.
Cheers, Gene Heskett
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page <http://geneslinuxbox.net:6309/gene>