[erlang-questions] HiPE performance gain (Was: Re: [erlang-questions] Erlang static linked interpreter)

[Matthias Lang]

On Thursday, January 20, Thomas Lindgren wrote:

> there are any palpable problems on a local setup, of course. I think
> Mattias Lang has noted that the emulator has grown quite a bit over
> the years, is that a problem for instance?

  Version   CPU             Stripped Emulator size
  -----------------------------------------------------------------
  R7B01     PPC (MPC860)    688364
  R8B       PPC             793372
  R9C       PPC             931804
  
  R10B      MIPS (Au1000)   1275960
  R11B      MIPS            1299212
  R13B04    MIPS            1691188
  R14B01    MIPS            1865192

Over the years I've used different compiler versions and different
options. For a while, I remember that hacking the Makefile for
the emulator to use -0s instead of -02 gave a decent performance
_increase_.

Usually, the application runs a bit _slower_ on each new version of
Erlang. Sometimes 5% slower. Sometimes not slower at all. I don't
recall ever seeing a speedup. We do our performance-critical work in
FPGAs or DSPs, so this doesn't bother us, but we notice.

I've assumed that what happens is that each new Erlang release is
tuned for increasingly faster CPUs, while our hardware doesn't change
as often. But I'm just guessing.

The Au1000 has 16kByte I-cache and another 16kByte D-cache, i.e. tiny
compared to what's in even modest PCs.

Matt