[Gems-users] Controlling ruby's bandwidth

[Philip Garcia <pcgarcia@xxxxxxxx>]

I have a problem I've been trying to solve.  When I'm using ruby to  
measure my memory performance, I end up in a situation where my  
memory bandwidth for a single stream of data is directly proportional  
to the memory latency I have set.  I am wondering if this situation  
is created by design, or if there's something I'm overlooking.
The overall memory bandwidth wouldn't be a problem if I were  
accessing multiple streams of memory, however when I'm accessing a  
single stream, I end up in a situation where reading the first cache  
line from stream S_0 takes the full memory latency, and all  
subsequent reads from that stream will also incur the full memory  
latency.
Does anyone know of a "simple" way to change how this is?   In  
theory, the second access should be much faster than the first, and  
should be a factor of only the memory bandwidth.  Is anything like  
this modeled within ruby, and if not does anyone know where it would  
make sense to add such a thing?
One way to offload this problem is through the use of prefetching,  
however I think I'd need to heavily modify how I do my "hardware"  
prefetching in my code.
I just wanted to see if anyone has come up with a reasonable solution  
to this problem, or if my best luck is to see to it that the hardware  
is issuing prefetches sufficiently early to avoid the bandwidth issues.
Phil