🚀 go-pugleaf

In article <PCG.92Dec19165907@decb.aber.ac.uk> pcg@aber.ac.uk (Piercarlo Grandi) writes:
>As far as I have read and seen with my eyes, let me insist, most
>"general purpose" codes have limited degrees of exploitable micro/macro
>parallelism, say 2 to 4. The underlying reason is that most such codes
>are about is serial tree/graph walking/updating.

I suggest you read the Butler et. al. paper cited [1] earlier by someone
in this thread. These authors claim that on an unrestricted data flow
machine, *general purpose* codes like gcc, li, eqntott, (taken from
SPEC89) have pretty high degree of parallelisms in them. Measured in
terms of IPC:

  gcc - 38
  espresso - 179
  eqntott - 300
  li - 162

Judging from these claims, the issue is not how much parallelism there
is but how cost-effective is it to extract it. As CPU resources
approach realistic values the sustainable issue rates on these codes
fall dramatically, (2-4). These are limits imposed by the
hardware/compilers. 


Vinod Grover

-not speaking for Sun.


[1] Butler, Yeh, Patt, Alsup, Scales, Shebanow, "Single Instruction
Stream Parallelism is Greater than Two", Intnl. Symp. on Comp. Arch
1991.