Free memory gives wrong result on linux

[b-spruck]

The free memory returned is not correct on linux. Problem: file system cache and buffers are counted as "free", but the system might not be able to free them on demand. Example: Any file residing in /dev/shm is counted as free memory.

reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=34e431b0ae398fc54ea69ff85ec700722c9da773

In osdMemUsage.c, summing of of items shoudl be replaced by the value of MemAvailable

[ralphlange]

But only if the system's kernel is new enough to provide it.

[b-spruck]

sure. is there a reason to stick to old kernels?

[ralphlange]

Many installation use RHEL etc. which tend to update conservatively.
In terms of platform compatibility, EPICS code usually has to support 10-15 years of OS/compiler history.

[b-spruck]

let me rephrase it, is there a reason NOT to support new kernel feature?

[b-spruck]

else if (strcmp(title, "MemFree:") == 0 ||
strcmp(title, "Buffers:") == 0 ||
strcmp(title, "Cached:") == 0) {
memfree += value * 1024;
found++;
}else if (strcmp(title, "MemAvailable:") == 0) {
memfree = value * 1024;
found=99; // sorry depends on order ...

[ralphlange]

I can't avoid not to think of reasons not to support new kernel features.

Yeah, something along that is obviously fine.