On 12/29/13 6:35 AM, "Ola Fosheim Grøstad"
<ola.fosheim.grostad+dl...@gmail.com>" wrote:
On Sunday, 29 December 2013 at 13:46:07 UTC, Dicebot wrote:
This is not true. Assuming skilled use and same compiler backend those
are equally performant. D lacks some low-level control C has (which is
important for embedded) but it is not directly related to performance.
That low-level control also matters for performance, when you have hard
deadlines. E.g. when the GC kicks in, it not only hogs all the threads
that participate in GC, it also trash the caches unless you have a GC
implementation that bypasses the caches. Sustained trashing of caches is
bad.
Yeah how about using deterministic deallocation in the inner loops -
that's the only place where it matters.
C has low-level, low resource usage defaults. While you can do the same
in some other languages they tend to default to more expensive use
patterns. Like D defaults to stuff like GC and thread-local-storage.
Defaults affect library design, which in turn affect performance.
(thread local storage requires either an extra indirection through a
register or multiple kernel level page tables per process)
It is my opinion that safety is the best default at least here; global
storage is very often an antipattern in singlethreaded applications and
almost always so in multithreaded ones.. I think C got it wrong there
and D is in better shape.
Andrei
