global variables as structure in VM.

John.Maloney at John.Maloney at
Sat Apr 6 00:53:35 UTC 2002

>There is no benefit under os-9 or 68k bsd for moving to a global structure.
>I'm 98% sure globals are addressed based on pc+displacement. So 
>actually the setup to get to the point of structure start + offset is 
>higher that the current code.

Is there any cost?

>Alas the GCC 68K compiler is *way* more efficient than CW, but we 
>can't get there from here. Other than installing some flavor of 
>Bsd/Aux/BSD on your 68K machine if you want a dedicated 68k squeak 
>machine. That of course might be a viable choice if you want to run 
>squeak as efficiently as possible on that type of hardware. A long 
>time back I mentioned squeak under os8.1
>did 859,845 + 40,106. but under linux 2.0.38 it
>did 1,219,512 + 58,368.

Wow, that's a huge difference!!! Sounds like the Mac runtime system
for 68K just isn't as efficient as the linux one. I once lost a bet with Dan
based on the performance of the 68K VM; I wouldn't have lost it with
the 68K Unix VM, I think...

	-- John

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