[Beowulf] opteron 248 vs dual-core opteron 275
hahn at physics.mcmaster.ca
Sun Dec 4 10:24:51 PST 2005
> on a one per-core basis. Will this performance be better on a
> 2proc./4cores node or on two 2proc/2node configuration. I am talking
threading is completely irrelevant. the only question is: under your
workload, will half the memory bandwidth per core hurt performance?
this is not answerable in general, since workloads can vary from
not to completely dram-dominated.
> On the other hand, it seems clear to me that heat dissipation of the
> dual-core configuration will be much better. Can anyone confirm that.
you don't get something for nothing. DC does amortize some hardware,
so there is a power savings there. but I think most people just look
at the TDP of SC and DC, and ignore the fact that the SC TDP is for a
higher-clocked chip. the actual dissipation of a SC at the same clock
of a DC (ie, a couple steps down from top) will be lower than the SC TDP.
> Does the dual-core cpu dissipate approx. the same heat as a single-core one?
no, not at the same clock.
> Are there many problems on the use of dual-core application by linux OS,
> or is it really a no-problemo thing as I have read?
there was a bug having to do with misunderstanding of whether the TSC on
DC was synced or not. but certainly no functional problems.
> BTW, we use our cluster mostly for computational chemistry calculations,
> mainly gaussian, turbomole, molcas and such.
I'd expect these to be mostly dram-limited, and thus _not_ especially
favorable for DC. worse yet is where the app is scratch-disk-limited...
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