On 11/24/05, Zbigniew <[EMAIL PROTECTED]> wrote: > Here's another interesting performance note, and I assure you > everything is compiled this time. > > I have a C function which returns a void * by reference (i.e. it takes > a void ** as argument). I was using let-location, but I found that if > you pass a #<pointer> object as a scheme-pointer, it works just as > well and is about twice as fast. > > Okay, now the interesting part. In numerous places, such as tcp.scm, > a string object is allocated and passed as a scheme-pointer so it can > be filled. This is the same as taking my #<pointer> example above and > changing it to (make-string 4), assuming 32 bit pointers. > > What I found is that replacing (##sys#make-pointer) with (make-string > 4) incurs a huge number of garbage collections and is slow. What's > more, using (make-byte-vector 4) does NOT have this problem! I have > no idea why, as the implementation looks nearly identical to me > (basically, ##sys#allocate-vector). These results are repeatable for > me. >
On what system are you running this? On a x86 Linux box the string-based version is actually running faster than the byte-vector based one. String-allocation may result in some waste of memory, since strings are 8-byte aligned, byte-vectors are not. But the allocation difference in your case is quite substantial, which is odd. cheers, felix _______________________________________________ Chicken-users mailing list [email protected] http://lists.nongnu.org/mailman/listinfo/chicken-users
