On 14 November 2006 01:51, Geert Bosch wrote:
> On Nov 11, 2006, at 03:21, Mike Stump wrote:
>> The cost of my assembler is around 1.0% (ppc) to 1.4% (x86)
>> overhead as measured with -pipe -O2 on expr.c,. If it was
>> converted, what type of speedup would you expect?
>
> 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.
To be fair, Mike was talking about multi-core SMP, not threading on a single
cpu, so given that CPU usage is at 100% now for most jobs, there is an Nx100%
speedup to gain from using 1 thread on each of N cores.
> The main place where threading may make sense, especially
> with LTO, is the linker. This is a longer lived task, and
> is the last step of compilation, where no other parellel
> processes are active. Moreover, linking tends to be I/O
> intensive, so a number of threads will likely be blocked
> for I/O.
I'm not really sure how this would play with SMP (as opposed to threading).
I don't see why you think threading could be particularly useful in the
linker? It's the pipeline of compiler optimisation passes that looks like an
obvious candidate for threading to me.
cheers,
DaveK
--
Can't think of a witty .sigline today....
