[racket-dev] [plt] Push #28239: master branch updated

At Tue, 25 Feb 2014 09:22:54 -0500, Sam Tobin-Hochstadt wrote:
> On Tue, Feb 25, 2014 at 8:34 AM,  <mflatt at racket-lang.org> wrote:
> >
> > eff53cd Matthew Flatt <mflatt at racket-lang.org> 2014-02-24 16:42
> > :
> > | treat FFI primitives like other primitives internally
> > |
> > | This change paves the way for JIT-inlining FFI operations
> > | such as `ptr-ref`. Even without JIT treatment, the change
> > | slightly reduces the overhead for calling FFI primitives.
> 
> Do you have benchmarks for the FFI that you used here?

The claim of reduced overhead was based on removing indirections
through scheme_do_eval(), as visible in a low-level profile of a
drawing loop.

Now that you ask, though, the change cuts about 25% of the time for the
loop below on my machine.

----------------------------------------

#lang racket/base
(require ffi/unsafe)

(define N 1000)

(define p (malloc N))

(time
 (for ([i (in-range 1000)])
   (for ([j (in-range N)])
     (ptr-set! p _byte j 42))))