hi all,
I have a E4900 with ultrasparc 4+@1.5ghz processors which is dualcore according to sun. But in the lom or in os its showing only 4 processors. If it is a dualcore it should be 8..I think..considering other platforms. or sparc dualcore processors show only a single processor for a dual core ?
any idea?
rgds
First sun doesn't claim this processor is dual core.
<quote>
Executing on Sun's Throughput Computing strategy, the dual-thread UltraSPARC IV processor marks the first milestone in Sun's Chip Multithreading (CMT) roadmap.
</quote>
It handles two threads, and switches between them in a similar manner to the way a single core on the UltraSparc T1 does. It is however only 1 core, it just maintains registers, context specific registers, and other state for 2 threads.
I don't own a Sun CMT machine so I don't know what it should show in the OS, but if the TI shows 8 cores then this should only show 1.
Hope that helps, by the way, you really should read the spec/manual to get this information, I mean if you have the money to buy a 4900 but don't know how many cores it has ....
> [UltraSPARC IV / IV+] handles two threads, and switches between them in a similar manner
> to the way a single core on the UltraSparc T1 does. It is however only 1 core...
UltraSPARC IV and IV+ are true dual-core processors, each of which execute an independent thread of execution (1 thread per core).They are do not have multi-threaded cores like UltraSPARC T1.
> But in the lom or in OS it is showing only 4 processors
Sun defines a "processor" as the physical device that plugs into a board, so many software utilities will report 4 physical processors being present.
If you want a list of all the virtual processors (which in the US IV+ case = cores) present in the system, try executing this command:/usr/sbin/psrinfo
You should see a list of each virtual processor and its status (all 8 of them, for your system).
> I don't own a Sun CMT machine so I don't know what it
> should show in the OS, but if the TI shows 8 cores then this should only show 1.
An UltraSPARC T1, by comparison, should report as one physical processor and 32 virtual processors.
My mistake, apologies, I answered that question particularly late after a busy day. David Weaver's information is as always 100% correct.
The UltraSparc iV+ is the Dual (UltraSparc III pipeline based?) core processor. Apologies to anyone who may have inadvertantly read my incorrect comment.
> I answered that question particularly late after a busy day.
Heh Matt -- been there, done that myself .... way more times than I can count ;-)
> The UltraSparc iV+ is the Dual (UltraSparc III pipeline based?) core processor
The original UltraSPARC IV (a.k.a. "Jaguar") processor in 2003 was exactly as you describe -- essentially two UltraSPARC III+ ("Cheetah+") cores on one die (chip), sharing the bus.
A lot of additional work went into UltraSPARC IV+ ("Panther"), which started shipping in 2004. Although it was derived from UltraSPARC III+, there were numerous pipeline enhancements that -- among other things -- really improved floating-point performance. The two cores in IV+ share a large on-chip L2 cache, whereas on IV the cores had completely separate caches. I believe that UltraSPARC IV+ was also the first SPARC processor to implement the POPC ("population count:") instruction in hardware (primarily benefitting certain classes of cryptographic applications).
