On 14 November 2006 15:38, Robert Dewar wrote:
> Geert Bosch wrote:
>
>> Given that CPU usage is at 100% now for most jobs, such as
>> bootstrapping GCC, there is not much room for any improvement
>> through threading.
>
> Geert, I find this a bit incomprehensible, the whole point
> of threading is to increase CPU availability by using
> multiple cores.
Geert's followup explained this seeming anomaly: he means that the crude
high-level granularity of "make -j" is enough to keep all cpus busy at 100%,
and I'm fairly persuaded by the arguments that, at the moment, that's
sufficient in most circumstances to get 99% of the benefit there to be had.
I suspect that the balance will tip when the number of cores starts to get
huge, and that at some time in the future we would benefit of the extra
parallelizability we could get from reducing the effective scheduling
granularity by threading the compiler.
cheers,
DaveK
--
Can't think of a witty .sigline today....
