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Home -> Community -> Mailing Lists -> Oracle-L -> RE: reading the SGA from my own program
Anjo,
I guess I realize I could set shmmax high and get a single segment, but I want my program to work on any old Oracle instance, not just one I set up special for it.
Are you saying that because segments can be noncontiguous, you have to count the space between segments where there is no segment allocated when you are counting up from the SGA base address to the address of the object you are seeking?
In my case the segments are noncontiguous. There are big gaps between each segment according to oradebug IPC. If I count space between segments, then the supposed location of session waits falls in the last segment. I'll play around and see what I find. Any hints are welcome.
Is there a better (more programmatic way) to map the segments' base addresses and sizes other than looking at the trace file from oradebug ipc?
Thanks,
Jeremiah Wilton
ORA-600 Consulting
http://www.ora-600.net
Your assumption is wrong. The fixed SGA contains variables that are known at
oracle compile time or point to structures in variable part. So the answer
is that generally speaking, all x$ are in the variable part of the SGA. Also
there may be multiple segments but they are contiguous in memory (not always
the case), so you will have to map/attach at least to the segments of the
fixed and variable part. A better trick you can pull is so set SHMMAX
extremely large, so the whole SGA will fit in one segment. That means that
every thing is attached (easy to do when you are on linux).
Anjo.
-- http://www.freelists.org/webpage/oracle-lReceived on Fri Aug 18 2006 - 18:38:00 CDT
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