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Re: Faster compilation speed

On Tue, Aug 13, 2002 at 10:26:41PM -0700, David S. Miller wrote:
> Because for the millionth time, it's not the performance of GC itself.
> It's the temporal and spatial locality problems of data accesses which
> is a fundamental result of using GC for memory allocation.

You havn't shown (or even provided guesstemates) how much temporal
or spacial locallity could be had by moving away from GC.  Exactly
how much garbage is created during compilation of a function, Dave?

Suppose we did do manual memory allocation and never created any
garbage whatsoever.  Suppose perfect temporal locality.  How much
spacial locality do we have, considering the pointer-chasing structure
of our IL?  My guess is not much.

The folks that are doing cache-miss studies and concluding anything
should also go back and measure gcc 2.95, before we used GC at all.
That's perhaps not ideal, since it's obstacks instead of reference
counting, but it's not a worthless data point.

The conclusion that RC will solve all our problems is not foregone.
I think we're better served trying to adjust the form of the IL so
that we do less pointer chasing, as Geoff suggested elsewhere in 
this thread.


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