Hello,
I am trying to measure memory available for "malloc" in my application.
From /proc/meminfo I have the following:

MemTotal: 1035372 kB
MemFree: 117488 kB
Buffers: 79140 kB
Cached: 499216 kB
SwapCached: 0 kB
Active: 511768 kB
Inactive: 360340 kB
HighTotal: 130744 kB
HighFree: 252 kB
LowTotal: 904628 kB
LowFree: 117236 kB
SwapTotal: 2048276 kB
SwapFree: 2048276 kB
Dirty: 96 kB
Writeback: 0 kB
Mapped: 388224 kB
Slab: 30412 kB
CommitLimit: 2565960 kB
Committed_AS: 636504 kB
PageTables: 3160 kB
VmallocTotal: 106488 kB
VmallocUsed: 3676 kB
VmallocChunk: 102336 kB
HugePages_Total: 0
HugePages_Free: 0
Hugepagesize: 4096 kB

I have very similar result from the "sysconf", however RedHat System Monitor reports used memory as 360M off ~1G, so they report "Inactive" memory as free...
Which one I should use as a limit for "mallocs" in my process, so that it
wouldn't "overrun" the system? E.g. does "malloc" allocate from "Vmalloc total", or from "Inactive"?
Thanks,
-V

Looking at that, looks like you've got 1GB RAM, 2GB swap.
That would be the absolute max, but you'd have to allow some RAM for the OS, assuming no other user processes in use.
At a rough guess, anything over 750MB and it'll start digging into swap, which will slow everything down.
Consider carefully just how much you need at any one time.

Why 750M, and not Committed_AS: 636504 kB?
Similar question: what is the largest size of memory I can allocate at once? Also 630M?
Thanks,
-V