Question

Can anyone advise of AIX system calls that can be used to programatically check memory usage? I’m working with a large multithreaded C++ app which is currently running out of memory (using 32 bit, large memory model on AIX 6.1) due to a large unlimited series of in-memory caches. I can certainly limit the caches’ growth, but it is difficult due to their complex structure to work out how large they’ve got; much better IMO just to assess how much memory the process is taking up and limit based on that.

Using the very large memory model is not a possibility due to the use of shared memory, and going 64 bit is also not feasible in the short term.

Answer 1

For AIX I found that the following work fine in my applications:

#include <unistd.h>
#include <sys/types.h>
#include <sys/resource.h>

// total physical memory (in bytes)
size_t total_memory = sysconf(_SC_AIX_REALMEM) * 1024;

// maximum resident set of the process
struct rusage usage;
getrusage(RUSAGE_SELF, &usage);
size_t used_memory = (usage.ru_maxrss)*1024);

I believe that using vminfo (/usr/include/sys/vminfo.h) you should be able to get the used memory system-wide.