Can the STREAM and GUPS (single CPU) benchmark use non-local memory in NUMA machine
- by osgx
Hello
I want to run some tests from HPCC, STREAM and GUPS.
They will test memory bandwidth, latency, and throughput (in term of random accesses).
Can I start Single CPU test STREAM or Single CPU GUPS on NUMA node with memory interleaving enabled? (Is it allowed by the rules of HPCC - High Performance Computing Challenge?)
Usage of non-local memory can increase GUPS results, because it will increase 2- or 4- fold the number of memory banks, available for random accesses. (GUPS typically limited by nonideal memory-subsystem and by slow memory bank opening/closing. With more banks it can do update to one bank, while the other banks are opening/closing.)
Thanks.
UPDATE:
(you may nor reorder the memory accesses that the program makes).
But can compiler reorder loops nesting? E.g. hpcc/RandomAccess.c
/* Perform updates to main table. The scalar equivalent is:
*
* u64Int ran;
* ran = 1;
* for (i=0; i<NUPDATE; i++) {
* ran = (ran << 1) ^ (((s64Int) ran < 0) ? POLY : 0);
* table[ran & (TableSize-1)] ^= stable[ran >> (64-LSTSIZE)];
* }
*/
for (j=0; j<128; j++)
ran[j] = starts ((NUPDATE/128) * j);
for (i=0; i<NUPDATE/128; i++) {
/* #pragma ivdep */
for (j=0; j<128; j++) {
ran[j] = (ran[j] << 1) ^ ((s64Int) ran[j] < 0 ? POLY : 0);
Table[ran[j] & (TableSize-1)] ^= stable[ran[j] >> (64-LSTSIZE)];
}
}
The main loop here is for (i=0; i<NUPDATE/128; i++) { and the nested loop is for (j=0; j<128; j++) {. Using 'loop interchange' optimization, compiler can convert this code to
for (j=0; j<128; j++) {
for (i=0; i<NUPDATE/128; i++) {
ran[j] = (ran[j] << 1) ^ ((s64Int) ran[j] < 0 ? POLY : 0);
Table[ran[j] & (TableSize-1)] ^= stable[ran[j] >> (64-LSTSIZE)];
}
}
It can be done because this loop nest is perfect loop nest. Is such optimization prohibited by rules of HPCC?
