[cfarm-users] Compile Farm acceptable usage---low priority batch jobs

[Segher Boessenkool]

On Fri, Jan 03, 2025 at 07:20:18PM -0600, Jacob Bachmeyer via cfarm-users wrote:
> On 1/3/25 03:23, tkoenig--- via cfarm-users wrote:
> >Am 03.01.25 um 02:40 schrieb Jacob Bachmeyer via cfarm-users:
> >
> >> I have a philosophical view that idle time on servers is essentially 
> >> wasted: a sunk cost.
> >
> >In the age of TTL, ECL or even NMOS, that might have been true, power
> >usage was pretty much independent of the computational load in
> >those days.
> >
> >Now we have CMOS and dark silicon, gate switching (aka computation)
> >determines energy consumption and the things that go with it (cooling
> >costs, semiconductor aging, etc).
> 
> For smaller machines,

No, mostly for huge machines.  Clocked stuff takes serious power; stuff
that doesn't change state takes close to zero power.  It has been like
this for over a decade now, close to two decades.

> yes, with a few caveats that not all architectures 
> actually do that:  if the clock is not gated off, the gates still 
> switch.  Larger systems tend (as far as I know) to be less likely to 
> actually take those power-saving measures.  The very newest models 
> probably do, however, I admit.

Clocks gated off is so 90's.  Nowadays we do much better (more general)
things.   But sure, do the biggest gains first.  But we are way way past
that nowadays.


Segher