[Beowulf] Altix vs. Beowulf

Joe Landman landman at scalableinformatics.com
Wed Apr 20 17:43:05 EDT 2005



Mark Hahn wrote:

>>Please note that several network cards also have build in shared memory at
>>the card. Quadrics has a shmem library for example at a real low cost for 8
>>nodes.
> 
> 
> a shmem library does not shared memory make.

long *big_honking_storage_pointer,
       billions_and_billions = 16 * 1024 * 1024 * 1024;
big_honking_storage_pointer	=
       malloc(billions_and_billions*sizeof(double));

/*
    ahhh global shared memory, tastes great, less filling, easy to
    program

  */

Basically if you cannot allocate a huge chunk of ram and have the OS 
figure out where to get it from without breaking the request up, then it 
really isn't shared memory.  If you cannot slide along contiguous 
address blocks on a single CPU and touch all of your ram, then it really 
isn't shared memory.

There is some sort of Jeff-Foxworthy type thing happening here.

---

Joe

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