Am 07.03.2012 13:11, schrieb Henry Vermaak:
On 07/03/12 12:02, Marco van de Voort wrote:
In our previous episode, Henry Vermaak said:
PS:
Adding any more (if possible) parallel compilation support would be
awesome too. This already saves me over 1 minute in compile time on my
quad core. Yes, I hate it if CPU's just sit idle.
IIRC add FPMAKEOPT='-T 3' (3= number of paralel threads)
This makes a big difference for me:
Without FPCMAKEOPT: 1m48.056s
With FPCMAKEOPT="-T 9": 1m13.833s
Unfortunately, cycling the compiler is taking really long and -j 9 isn't
helping much (or at all).
fpmake only handles packages/.
fpmake (or make -j the way FPC used it in the past) can't really speed up
runs that are a single compiler invocation (like the compiler), unless it
can run two such runs in paralel.
In packages this is possible, in the compiler cycle compiler depends
on RTL,
and the "next" rtl depends on the "previous" compiler, so nothing can be
done there.
To exploit paralellism in single compiler invocations, threading
should be
brought into the compiler, but that is an huge and uncertain job.
With c, the compilation of .c -> .o is isolated, so many of them can be
run in parallel, which means that compiling e.g. the linux kernel, you
get great performance from make -j %d. Is it possible to have fpc do the
same thing somehow? Bringing threading into the compiler sounds very
scary, indeed.
In C the dependencies between the .o files are resolved at link time
while in Pascal they are already resolved at compile time (the unit
concept). So the only feasible possibility for a speed up there is
threading support in the compiler as only the compiler fully knows the
dependencies between the units.
Regards,
Sven
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