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--- hpc:bghep:benchmarks [2014/02/17 19:31]
asc [Fig 3]
+++ hpc:bghep:benchmarks [2014/05/27 16:45] (current)
edmay
@@ Line 48: / Line 48: @@
 R == sec/event  =       job_run_time/total_number_of_events
 Nc == number of cores used in job
-<code>
+</code>
 For a perfect speed-up this would always be 1. My experience with clusters of
@@ Line 61: / Line 61: @@
 {{:hpc:bghep:alcf-vesta-pythia6-promc-mpi-d.png?400|}}
+The ALCF experts suggested the I/O model of 1 directory and many files in that 1 directory would preform badly due to lock contention
+on the directory! Thus the example code was modified to use a model
+of 1 output promc data file per directory. Running the modified code
+produced the following figures:
+http://www.hep.anl.gov/may/ALCF/new.vesta.4up.pdf Vesta Plots
+Focusing on the 'Efficiency' plots there appears to be some (small)
+improvements both at low core numbers and a high core numbers: 80% rising to 90% and 20% rising to 40% respectively.
+The large step between 512 to 1024 is still present!
+As part of the bootcamp for MIRA the code was moved to the
+BG/Q Mira and a subset up the benchmarks were run in the new
+IO model. The results are shown in
+http://www.hep.anl.gov/may/ALCF/new.mira.4up.pdf Mira figures
+Again focusing on the Efficiency plot the results are very
+similar. This suggest when using this naive IO model of each
+mpi rank writing its own output ProMC file should be limited to
+jobs of 512 cores or less for good utilization of the machine
+and IO resouces. This is OK for Vesta where the minimum charging
+is 32 nodes (ie 512 cores). While on Mira the minimum is 512
+nodes (ie 8192 cores) there is not a good match!
 [[hpc:bghep:| << back]]
- --- //[[[email protected]|Ed May]] 2014/02/04 10:42//
+ --- //[[[email protected]|Ed May]] 2014/02/04 //
+ --- //[[[email protected]|Ed May]] 2014/05/27 //
  --- //[[[email protected]|Sergei Chekanov]] 2014/02/04 10:42//

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