PDA

View Full Version : For licensing purposes, how does TotalView count processors?



Tom-TotalView-Tech
02-22-2007, 12:38 PM
From TotalView's perspective, a processor is one independent processing unit regardless of the physical packaging. If a processing unit can execute one instruction thread while another processing unit can simultaneously and independently execute another distinct instruction thread (without time-sharing resources), then we treat them as two processors.

In the case of a hyper-threaded processor, separate and distinct instruction threads may appear to be running simultaneously, but since processing hardware is time shared, we consider only the processing core itself. If a package contains 2, 4, or more cores then the processor count would be equal to the number of cores.

As a simple example, an Intel Pentium processor package contains only a simgle process unit. Consequently, TotalView sees this package as a single processor.

Another example: I have an Intel Centrino Duo T2400 in my laptop. When TotalView executes on this platform, it sees the dual cores in the T2400 and counts two processors.

As an extreme case, Sun has introduced their Niagara processor chip which contains eight cores with each core supporting four hyper-threads. Potentitally, this processor chip can support a total of 32 threads, but Etnus recognizes the time-sharing aspect of hyper-threading and thus, TotalView counts the number of cores and correctly classifies this processor chip as equivalent to eight processors.