[m-dev.] why append slows down using lco

Thomas Conway conway at cs.mu.OZ.AU
Wed May 26 19:18:25 AEST 1999

On Wed, May 26, 1999 at 03:32:02PM EST, David Overton wrote:
> > Tyson suggested that the problem is due to the fact that when we create
> > the cell on the heap the tail cell contains garbage which the boehm gc
> > garbage collector may interpret as a pointer.
> > Setting the tail cell to zero gives us the required speedup,
> > if only just!
> > 
> > run.nolco.vn:       251950 ms
> > run.lco.vn.zero:    249833 ms
> > 
> I'll change the code generator to do this.

Make sure it has a separate switch to enable or disable this
since the accurate collector (when it copes with such data structures)
won't need the cell to be zeroed and so you can avoid the work.

 Thomas Conway  )O+  |  Team Register has a Pentium III. Its serial number is
     Mercurian       |  00000672000226FA025D71BF. We are not afraid.
<conway at cs.mu.oz.au> |    -- from http://www.theregister.co.uk
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