[SunRescue] SS4/SS5/SS10 funzies.....(:+}}...

[James Lockwood]

On Tue, 3 Apr 2001, Joshua D. Boyd wrote:

> So, how does a 80mhz SuperSparc supposedly compare to the 170mhz chips in
> SS5s?  If any machine were possible, what is that fastest non-ultra CPU
> sparc available?  Is there anything as dramatic as the difference between
> the 150mhz R4400 vs the 75mhz R8000?

Sun didn't ship production 80MHz SuperSparcs.  The SM81 (85MHz) probably
holds fairly even with the 170MHz TurboSparc, with a boost to code that
fits the Supers cache better (1MB vs 512KB).  The microSparc-II based
sun4m's have lower memory latency across the board so truly cache-busting
code on a SS5/110 may actually beat out everything else.

For "typical" apps, a SS20 with HyperSparcs will be hard to beat.  A
150+MHz Hyper will outperform the Supers for most code and a 200 should
for everything except very rapid context switching (virtual vs physical
cache mapping bites the Hyper here, it will have to do more cache flushes
on average).

The R8k is a funky chip.  It's great at certain benchmarks and a very
narrow (FP intensive) opcode mix.  Stay within that and you get terrific
performance, stray outside and it goes into the toilet.  Faster R8k's
(such as used in the Power Challenge series) were better balanced but the
R8k/75's used in the Indigo2's do not offer a huge performance boost over
the R4400's.  I'd rather have a 200+MHz R4400 than the R8k/75.

Of course, if you wanted a "stealth" Ultra, you could always get a
SparcEngine Ultra 20 and put it into a SS20 case.  Rare boards though.  :)

-James