[GE users] Difference between "qhost MEMUSE" and "free -m"

futurity neil at futurity.co.uk
Tue Feb 17 12:58:22 GMT 2009


Hi,

I'm using Grid Engine 6.1u3.

I've been told that the qhost MEMUSE value should match the value returned
by "free -m".  However, I'm noticing a difference between the "free -m" Mem
used value and the "qhost" MEMUSE value for execution hosts.

2661 MB compared to 381 MB in one instance.

I know the qhost host value is a snapshot value updated every minute, so I'm
comparing values at the time this snapshot is taken.  I know these values
will never be exactly the same, but these differences seems to be very
large.

I run the command below on a particular execution host to get the values:

# free -m ; qhost | grep stg-dell40

             total       used       free     shared    buffers     cached
Mem:          4048       2661       1387          0        345       1951
-/+ buffers/cache:        363       3684
Swap:         2047         50       1997

stg-dell40              lx24-x86        8  2.01    4.0G  381.2M    2.0G
50.6M

The "free -m" Mem used (2661 MB) does not match the qhost MEMUSE value
(381.2 MB).  

I've even run it an hour later with top included:

# free -m ; top -b -n1 ; qhost | grep dell40
             total       used       free     shared    buffers     cached
Mem:          4048        667       3381          0         29        449
-/+ buffers/cache:        188       3860
Swap:         2047         51       1996

top - 12:50:03 up 117 days, 21:42,  1 user,  load average: 1.29, 1.83, 3.42
Tasks: 155 total,   2 running, 153 sleeping,   0 stopped,   0 zombie
Cpu(s):  5.0%us,  0.3%sy,  0.7%ni, 93.2%id,  0.8%wa,  0.0%hi,  0.0%si,
0.0%st
Mem:   4145700k total,   683584k used,  3462116k free,    30408k buffers
Swap:  2097136k total,    53056k used,  2044080k free,   460484k cached

stg-dell40              lx24-x86        8  1.87    4.0G  182.5M    2.0G
51.8M

Again the "free -m" Mem used (667 MB), confirmed by top, still does not
match the qhost MEMUSE value (192.5 MB).  

Any idea why these values differ?

Neil

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