Thanks Rick for the message.

My machine is a HP server rx4640 (
http://h18000.www1.hp.com/products/quickspecs/11847_div/11847_div.HTML) with 4 montecito processors. I understand this is a single-bus system.

I run up to 8 threads (of a maximum 16) so as not to 'invoke' hyperthreading. Then measure BUS_DATA_CYCLE_ANY to calculate bus utilization. My intention is to see if the benchmark is saturating the memory bus with off-chip accesses.

Vineeth

On 06/28/2010 03:52 PM, Rick Jones wrote:
Vineeth Mekkat wrote:
Hi All,

I am trying to measure bus utilization of some benchmarks on Itanium Montecito machine. I followed the procedure in http://www.ice.gelato.org/oct06/pres_pdf/gelato_ICE06oct_perfmon2_eranian_hp.pdf and measured the bus utilization. Now, I am not sure at what percentage of value is the bus saturated? Is it 100%?

What sort of system are you measuring?  A single-bus system, or a "cell-based" system?

Say, if my bus utilization is 75%, can I say the bus is saturated?

I will be grateful if someone can shed some light on this.

I'm not sure how much light I will shed, but when it comes to memory busses, I've never been comfortable much past 80%.