Pavan, Where did you get this threads.c test? The messaging rate benchmark that Sameer had sent is different. See attached mail. Rajeev
-----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Pavan Balaji Sent: Tuesday, January 29, 2008 3:53 PM To: [email protected] Subject: [mpich2-core] MPICH2 Threading Overhead
Hi all,
I've run some experiments for the MPICH2 threading overhead on BG/P and Breadboard (test program is attached). I don't remember if IBM reported that the performance stays constant with increasing threads or if it degrades, but I'm noticing a drop in performance (results below).
On BG/P, this is slight yet noticeable, but on breadboard it's drastic. Note that 1 thread refers to "no extra threads" -- the main process does a self send/recv.
This is not the fairest comparison since MPICH2-BG/P is based on MPICH2-1.0.4p1, while the breadboard runs are on MPICH2-trunk. I'll try out MPICH2-1.0.4p1 on breadboard as well. But as a longer term solution I'm trying to get MPICH2-BG/P ported to MPICH2-trunk so that I can easily try out any threading enhancements that might go in to trunk from here on.
Thanks.
-- Pavan
-------------------------------------------------------------- -----------
BG/P: ---- # MPI Message Rate Test with 1 Threads # Size Latency (us) Message Rate (MMPS) 0 1.38 0.725 # MPI Message Rate Test with 2 Threads # Size Latency (us) Message Rate (MMPS) 0 3.59 0.557 # MPI Message Rate Test with 3 Threads # Size Latency (us) Message Rate (MMPS) 0 5.75 0.522 # MPI Message Rate Test with 4 Threads # Size Latency (us) Message Rate (MMPS) 0 7.93 0.504
Breadboard: ---------- # MPI Message Rate Test with 1 Threads # Size Latency (us) Message Rate (MMPS) 0 0.17 5.774 # MPI Message Rate Test with 2 Threads # Size Latency (us) Message Rate (MMPS) 0 1.69 1.180 # MPI Message Rate Test with 3 Threads # Size Latency (us) Message Rate (MMPS) 0 7.54 0.398 # MPI Message Rate Test with 4 Threads # Size Latency (us) Message Rate (MMPS) 0 2.04 1.963
-- Pavan Balaji http://www.mcs.anl.gov/~balaji