Re: XY and Memory Weirdness

[Robert Holmgren holmgren@xxxxxxxx]

** Reply to note from scarter@xxxxxxxx (Stephen A. Carter) Sat, 25 Jan 1997 22:32:37 +0900
 
> In the case you describe, though, some of the instability you
> experienced might be due to running OS/2 with the external CPU cache
> enabled. Warp takes care of that kind of caching automatically, so
> the BIOS settings for external caching should always be off. 
> (Though it's perfectly fine and probably advisable to leave internal
> caching enabled, if the system supports it.)

Interesting. I know little about caches, but opinions sure seem to differ re:
L2. Some say, that if you need to turn L2 off in order to install OS/2, then
leave it off. Others say that problems arise only when L2 is configured for
read-through rather than write-back caching. Still others swear by L2
and claim huge performance benefits when they raise L2 cache size from,
say, 256 to 512K. Whereas, there's a rumor that Intel's gonna dump L2 in the
next generation processor. I see no difference at all on my machine, enabled or
disabled, though I can't claim any scientific "tests". All very confusing. I
conclude that L2 has very machine-specific effects. You have no hesitation about
the broad prescription to disable it? Do you know whether these effects are
applicable in other OSs as well? I'm running multiple OSs, and I can't be
toggling BIOS settings each time I change OS, because L2 is beneficial in one
and harmful in another.


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Robert Holmgren
holmgren@xxxxxxxx
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