compile times...

[Bill Elgie]

In article <6709 at hubcap.clemson.edu>, hubcap at hubcap.clemson.edu (Mike Marshall) writes:
> A prof here is running benchmarks on everything that isn't tied down.
> 
> He told me that his benchmark program ran on my DECstation 3100 as fast as
> it did on an IBM 3081 mainframe. But, he said, it took forever to compile.
> 
> It compiles on our VAX-8810 running ULTRIX in about 20-30 seconds. On my
> workstation, it took about 8 minutes to compile.
> 
> I am assuming that the reason that it takes so long on on my workstation 
> can be attributed to the fact that RISC compilers have so much more work
> to do than "regular" compilers.
> Does my evaluation seem on the mark to you all, or is there probably more
> to it?

  I would say that there is more to it.  While compilers on RISC systems may
  have to do "more work", I would say (based on the fact that we compile the
  same code frequently on both MIPS-based and VAX-based processors) that the
  ratio is less than 2:1 and often close to 1:1 .

  The major difference that you saw (8810 vs 3100) is more likely due to lack
  of memory.  I would guess that you have somewhere between 8 and 12 meg in 
  the 3100 and all the windowing software would take 6 meg or so of that.  The
  8810 probably had at least 64 meg.

  To illustrate, the following is an "excerpt" from a set of benchmarks that
  we ran recently.  This shows average elapsed time per compile for 1-8 simul-
  taneous compiles.  The MIPS M/120, which uses the same processor as the 3100,
  has 16 meg memory; the 8550 has 32.  "O2" level optimization was used on the
  MIPS ("O1" would have run apx. 20% faster).

   System     1 compile   4 simult. compiles     8 simult. compiles

  MIPS M/120     102            360                    804

  VAX 8550       107            323                    645

     greg pavlov (under borrowed account), fstrf, amherst, ny