> Well, do not believe this techie, do a simple calculation: A P90 has
> 90 Mhz, a P-II400 has 400Mhz 400/90=4.44 - so you have a speed
> increase of a factor 4 - Ok, i know, this is just the processor speed
> but including the fact that the P90 has no MMX, no onboard cache
> (what is important for SMP systems), no 100Mhz front side bus etc you
> will achieve a speed increase of at least 5 compared with a
> dual P90.
Well, it depends. my Dual P 133 is still more responsive then my
Single PII 300. both have the same amount of RAM . if you are only doing
calculations, or playing quake II, then yes, just go for pure speed
(newest processor), but you need to remember that with Linux 2.2 both
processors can handle interupts at the same time, hence TRUE multi-tasking
not task switching that goes on with uniprocessor machines that emulates
runing multiple tasks at the same time. it very well may be taht a Dual
Pentium 90 may outperform a Single PII 300 for server processes. now the
cases where this happens would be rare, but conceaviable. but as pointed
out above, the P5 memory buss is not nearly as good as the PPro/PII/PIII
memory buss.
>
> Once again, the fact that the P90 has no second level cache on chip
> makes this processor perform bad in SMP systems. I run at home a
> dual P200 system and a dual P-II 233 system. When I compile my
> linux kernel with "-j2" I get a speed increase of around 90-95% on
> my P-II but only around 50-70% on my P200.
> On the other hand I have to state that in some _rare_ cases a small
> on chip second level cache can also be an advantage but this will
> not apply to most applications.
>
Technicaly, the PII/PIII dosent have on chip L2 cache. The only
processors out that do have this are the Intel Celeron, some moble PIIs,
and the K6-3. of these, the moble PIIs and the K6-3 are the only ones
that have enough cache to be concidered for a serious Dual system, and
nether of these will go multi-processor (although with a LOT of hardware
hacks I guess you could get the moble PIIs to go dual). While the
Celerons can be used in dual systems, I wouldent do it because of there
small cache size (unless you only wanted to play around with SMP and not
use it as a production machine). The PPro/PII family does have a few
advantages over the P5 family as far as Cache goes. these processors run
there cache at eather half or full speed of the processor, while the P5
family is limited to 66Mhz. also most Dual P5 boards use a unified cache
that shares the cache between each processor, while the PPro/PII family
each processor has its own L2 Cache.
As far as OS goes, this list is going to give you a one sided opinion.
personaly, I think NT does rather well on Dual machines. I think this is
where NT is happy. on Single processor machines NT sucks, but on dual
machines it is tolerable. of course I dont recomend NT, as it has no true
remote administration ability and is unstable as hell (yes even under DUal
processor machines I got many BSODs ). NT will goto 4 processors in the
Server edition, but only 2 processors with NT workstation. of course dont
even think of Win 9x for a Dual machine, that is like running a V8 with
only 4 spark plugs in the engine.
My sugestion would be a Dual PII 350 or 400 with 128Megs of ram. I
personaly like Tyan boards, but they can be picky about the memory that
they use (use good ECC SDRAM with Tyan boards).
Cris Wade
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