[GE users] Grid Engine vs. Java Jobs

Iwona Sakrejda isakrejda at lbl.gov
Wed Nov 30 22:29:00 GMT 2005


Hi,

I read diligently through this thread and I wanted to add that we have
kernel version 2.4.21-27.0.2 and system version similar to reported
in this thread (SL 3), SGE 6.0u4 and we observe memory reporting problems with all
threaded applications.

One of my colleagues wrote a simple program to test it and here are his conclusions:
"I believe that processes are what is schedulable under linux and each thread is reported as a 
separate process under this linux version.  However, linux is also reporting the total memory usage 
across all threads for each thread.  That is, after each new thread, the memory usage reported for 
each thread increases by the user's stack size ulimit.  So, summing across all threads which is what 
I'm guessing SGE is doing over counts.  The right thing to do is to determine which processes are 
actually part of a thread group, and count memory once.  I don't know whether or not this info is 
available from the kernel you're running but I'd think it's worth a query to the SGE people in any 
case to see what if anything they can do about it."

So could anything be done about this problem? I did not see any resolution of the
e-mail discussion.....

For now I advise users having threaded applications to ask for huge amounts of memory
if they know what they are doing to overwrite my 1GB default, but that's awkward and dangerous...

Thank you...

Iwona



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