[GE users] maxvmem in accounting

Ross Dickson Ross.Dickson at dal.ca
Fri Apr 25 17:22:54 BST 2008


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Hi Grid Engineers.

The maxvmem that appears in the accounting file and in 'qacct -j' --- 
can anyone explain that better than 'man accounting' does?

We initially assumed that this number would be commensurable with 
h_vmem, in the sense that the maxvmem recorded for a job could be 
re-used later as a suitable value for h_vmem on a similar job (with a 
suitable safety margin).  Then we realized that a parallel job reports a 
variety of maxvmems, and we're now not clear what entity each one refers to.

"Each job is represented by a line in the accounting file."  Well, for 
serial jobs, maybe.  For parallel jobs, it's something more like one 
line per sge_shepherd, plus one for ... what?  Does qmaster write the 
last one?  Does every sge_shepherd write a line, or does it depend on 
the conditions?  What conditions?  We're operating a research 
environment with a wide variety of codes running, so we need to 
understand how both process-parallel (e.g. MPI) and thread-parallel (e.g 
OpenMP) jobs get accounted for, as well as tight- versus loose-integration.

"maxvmem:    The maximum vmem size in bytes."  My reading of other 
sources tells me "vmem" represents the size of the address space of the 
process.  Am I missing anything subtle here?  (It appears to me the 
relation between the size of the address space and the physical memory 
required may be complicated, unfortunately.)

Oh, and please don't recommend we get Arco.  We tried that last year, 
and it went so badly that management is really not inclined to give it 
another go.


Thanks.

-- 
Ross Dickson         Computational Research Consultant
ACEnet               http://www.ace-net.ca
+1 902 494 6710      Skype: ross.m.dickson


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