[plt-scheme] 301.4

From: Jim Blandy (jimb at red-bean.com)
Date: Wed Feb 1 00:39:56 EST 2006

On 1/30/06, Matthew Flatt <mflatt at cs.utah.edu> wrote:
> For now, typical speedups from JIT compilation are in the range 1x
> (i.e., no speedup) to 1.3x, with an occasional 2x or 4x. The JIT rarely
> slows any program --- though, of course, it's possible.

Are you comparing the JIT to mzc, or to the bytecode interpreter?

If the interpreter, I'm surprised.  are there bytecodes for which you
emit slower code than the interpreter path for that bytecode?  Or does
a lowered instruction cache hit rate eat your gains?

Don't get me wrong --- this is a great hack.  But for goodness' sake,
why would one plunge into the hair and non-portability of native code
generation if one doesn't get a nice hefty speed boost from it?  That
is, why isn't the bytecode interpreter a sufficient stopgap until the
"real thing" is ready?

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