Toon Knapen wrote: > Geoff Jacobs wrote: >> >> If an application is going to be using only shared memory, I have no >> doubt the consensus here is to use native threads or OpenMP. If the >> application is going to be working over a network, MPI (or PVM) is the >> way to go. > > > If threads are better for SMP, but what about Numa like SGI Altix or HP > Integrity ? On the latter for instance, inter-cell (cell = 1 board with > 4 cpu's) memory access suffers 200 times higher latency compared to > intra-cell memory-access. > > But also the AMD (and future Intel) processors are Numa. With threads > you have no idea about referencing remote memory but is that a good thing? > > And considering that future processors are even going more extreme in > the Numa direction (e.g. the Intel 80-core), is'nt it more future-safe > to go with MPI if one would start a large coding-project now? > > thanks for all the reactions, > > toon I do physics and computing. I am not a system programmer, so take this with a grain of salt. However, it seems to me that a sufficiently intelligent operating system would be able to attach the thread local store to the local memory pool.
I've used a Superdome before (FORTRAN and HP MPI), so I know whereof you speak, but MPI is not the general rule for software development in both the Windows and UNIX world. Using the complexity of MPI isn't very popular when a simpler method works okay. However, it seems like threads have taken a little beating lately in favor of discrete address spaces in security conscious system software (most famously, DJBs stuff) which communicate with pipes and shm. And lessons from QNX and BeOS tell us we might see some resurgence in the use of message queues and other means of low level message passing in the standard library. -- Geoffrey D. Jacobs _______________________________________________ Beowulf mailing list, Beowulf@beowulf.org To change your subscription (digest mode or unsubscribe) visit http://www.beowulf.org/mailman/listinfo/beowulf
