Thanks for the reply, Tomasz.
We have now done some more performance tests working with pure C/C++
code, and the results we are finding seem to indicate that the disk
thrashing has to do with the OS disk cache, and not as a result of the
lo_open call. Notably, we have been unable to recreate the problems we
found with the size of the shared buffers affecting performance, which
confirms Tom's conclusions.
We still have a performance issue, but the latest round of tests
indicate a number of places we should try to tweak.
Thanks for your patience, Tom.
Database Architect, met.no
Tomasz Ostrowski wrote:
> On Tue, 22 Jan 2008, Michael Akinde wrote:
>>> What I *do* see is that the process size as reported by "top"
>>> quickly jumps to 900MB plus and then sits there. This is not a
>>> memory leak though, it is just a side effect of the way "top"
>>> reports usage of shared memory.
>> Also, since the blob is opened and closed, why does the process allocate
>> new memory to open a new blob, rather than reuse existing memory?
> I think a process does not allocate new memory, it just uses his
> shared buffer. The OS does not give physical memory for a process
> immediately when it is allocated for example by malloc, it gives it
> in chunks - only when it is first read or written to.
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