[mpich-discuss] PVFS2/OrangFS with ROMIO ( perf.c )

[Rajeev Thakur]

You need to give the full path to the file, /mnt/pvfs2/testfile. The pvfs2: prefix should not be necessary, but you can try with and without the prefix (and give the full path).

Rajeev


On Jul 18, 2012, at 2:25 AM, Ammar Ahmad Awan wrote:

> Dear All,
> 
> I am very new to parallel file systems. I am trying to learn how to
> use PVFS using ROMIO. The romio source has a test directory which
> contains perf.c file.
> 
> I am compiling perf.c as follows
> 
> mpicc perf.c -o perf.o
> 
> I run it like
> 
> mpirun -np 2 ./perf.o -fname tesfile
> 
> This works fine and gives me the results as
> 
> Access size per process = 4194304 bytes, ntimes = 5
> Write bandwidth without file sync = 2751.942262 Mbytes/sec
> Read bandwidth without prior file sync = 5796.239765 Mbytes/sec
> Write bandwidth including file sync = 198.921236 Mbytes/sec
> Read bandwidth after file sync = 5482.750327 Mbytes/sec
> 
> I want to run it so I can test the performance of my PVFS2
> installation. PVFS2 is mounted in /mnt/pvfs2 as per the quick start
> guide along with a loaded  kernel module.
> 
> My question is when I execute the same perf.c with "pvfs2:" before the
> filename like
> 
> mpirun -np 2 ./perf.o -fname pvfs2:tesfile
> 
> The results that I get are strange. Very high bandwidth but the file
> is not created on /mnt/pvfs2. What is the reason that the test
> executes but gives the PVFS_util_resolve error and also I cannot see
> any file being created on /mnt/pvfs2?
> 
> Access size per process = 4194304 bytes, ntimes = 5
> PVFS_util_resolve: No such file or directory (error class: 0)
> Write bandwidth without file sync = 657930.039216 Mbytes/sec
> Read bandwidth without prior file sync = 657930.039216 Mbytes/sec
> PVFS_util_resolve: No such file or directory (error class: 0)
> 
> Write bandwidth including file sync = 532610.031746 Mbytes/sec
> Read bandwidth after file sync = 729444.173913 Mbytes/sec
> 
> If I give the full path to the file in the same test like this
> 
> mpirun -np 2 ./perf.o -fname /mnt/pvfs2/testfile
> 
> The performance reduces and results are :
> 
> Access size per process = 4194304 bytes, ntimes = 5
> Write bandwidth without file sync = 974.060381 Mbytes/sec
> Read bandwidth without prior file sync = 1306.128143 Mbytes/sec
> Write bandwidth including file sync = 103.729221 Mbytes/sec
> Read bandwidth after file sync = 1261.634532 Mbytes/sec
> 
> Can anyone tell me what is the difference between these two methods of
> executing ROMIO programs.
> 
> 1. using the pvfs2: prefix before the filename
> 2. using the full path to specify the filename without pvfs2: prefix
> 
> Which is correct? Both are same?
> 
> Kind Regards
> -- Ammar
> ----------------------------------------------------------------------
> Masters Student
> Dept. Of Computer Engineering,
> Kyung Hee University, South Korea
> ----------------------------------------------------------------------
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