Hi!
If they are 8 core Intel machines, I believe this is the case:
*) Each pair of cores share an L2-cache. So using two cores that share
cache will probably reduce performance.
*) Each Quad core CPU has its own memory bus (Dual independent bus),
so using more than one core on a quad CPU can
Are these intel-based machines? I have seen similar effects mentioned
earlier in this thread where having all 8 cores banging on memory
pretty much kills performance on the UMA-style intel 8 core machines.
I'm not a hardware expert, but I've stayed away from buying 8-core
servers for exac
Hi,
> A) The execution time in case "1" should be smaller (only sm
> communication, no?) than case "2" and "3", no? Cache problems?
Shot in the dark from working on Sun T1 (also 8 real cores): from time
to time the OS wants to do something (interrupt handling, wake up
cron, ...). Leaving one or
Jed Brown escribió:
On Mon 2008-09-29 20:30, Leonardo Fialho wrote:
1) If I use one node (8 cores) the "user" % is around 100% per core. The
execution time is around 430 seconds.
2) If I use 2 nodes (4 cores in each node) the "user" % is around 95%
per core and the "sys" % is 5%. The exe
On Mon 2008-09-29 20:30, Leonardo Fialho wrote:
> 1) If I use one node (8 cores) the "user" % is around 100% per core. The
> execution time is around 430 seconds.
>
> 2) If I use 2 nodes (4 cores in each node) the "user" % is around 95%
> per core and the "sys" % is 5%. The execution time is ar
Hi All,
I´m doing some probes in a multi core (8 cores per node) machine with
NAS benchmarks. Something that I consider strange is occurring...
I´m using only one NIC and paffinity:
./bin/mpirun
-n 8
--hostfile ./hostfile
--mca mpi_paffinity_alone 1
--mca btl_tcp_if_include eth1
--loadbal
