odd memory_usage() results

[eluser]jedd[/eluser]
Entirely concur wrt wanting to explain weird behaviour.

If you're running a GNU/Linux distro, pick one of the larger-memory laptops, and force the kernel to utilise less memory (mem= at boot). If you're using MS - no idea if you can fake it similarly. There might be a correlation between vm, not just physical RAM, so you might try forcing a smaller-memory box up with a hideous amount of swap, and vice versa.

Note that memory usage influences performance - especially when number of concurrent processes x footprint per process approaches available memory.

I can't really accept that this happens just because the difference in specs. That would mean that PHP's memory allocation algorithm is seriously flawed, why would it report a 2 meg difference in memory consumption when processing exactly the same code, running the same queries, producing the same results?

I don't know if this is the case .. but from an academic point of view, it's actually pretty smart - to use more resources if they're available.

Does the elapsed_time inversely correlate with the memory usage figures you're getting out of the profiler?