/proc doesn't really tell you much about userspace concerns such as "how much memory has the malloc implementation handed out to the program. It describes only

/proc doesn't really tell you much about userspace concerns such as "how much memory has the malloc implementation handed out to the program. It describes only the kernel-userspace parts of memory usage. For example, malloc fragmentation is not inspectable in it. (If you enable the mallopt() setting that turns each malloc() into a separate mmap(), then it tells you a lot, but that is not a default setting.)