id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc
3614	Much larger memory consumption of OMC under Linux than under Windows	Francesco Casella	sjolund.se	"The memory allocated by OMC under Linux is much larger (typically a factor four) than under Windows.

As an example, get the {{{ScalableTestLibrary}}} and run the attached test script.

On Windows 7 64 bit (with omc still running in 32-bit emulation), the maximum memory allocation by omc is about 560 MB. On Linux Ubuntu 64 bit, it goes well beyond 2000 MB. Please note that this memory is real, not virtual or shared - if the RAM of the machine is smaller than that value, the OS starts swapping wildly onto disk. 

We have experienced this behaviour extensively with larger models on a 64 GB server (you can also try out bigger models from the ScalableTestSuite library). In this latter case, the total memory allocation reported by {{{htop}}} is up to 40% larger than the one attributed to the omc process, possibly triggering massive disk swapping activity if the physical RAM boundaries are exceeded. What is quite weird is that, if the omc process is killed, this extra memory remains allocated, and is only very gradually reduced to zero. Who allocates and deallocates this extra memory and why is quite mysterious.

I am not sure how much of this is due to going from 32 to 64 bits, and how much it is OS specific. In any case, with larger model, this penalty is really unacceptable.

Please make sure that, at least optionally, the memory consumption under Linux matches the one under Windows."	defect	closed	critical	1.12.0	*unknown*		fixed		andrea.bartolini@…