Used memory was calculated as Total - Available.
For newer kernels (3.14+), available memory is taken from /proc/meminfo,
whereas for older kernels it is computed as free+buffered+cached.
This commit changes that behavior. Available memory is still taken from
/proc/meminfo, if available, but used memory is always computed as
total-free-buffered-cached.
This way, it matches the output of `free` for used memory (in the -/+
buffers/cache line) and other tools.
Prior to this change, I'd see a reported used memory of 600MiB whereas
free, htop and other tools would report a used memory of 1.8GiB. And
adding used, cached, buffered and free memory would leave ~1.2GiB
unaccounted for.
Package common wasn't used for public functions. Place it in an
internal directory to prevent other packages from using.
Remove the distributed references to "HOST_PROC" and "HOST_SYS"
consts and combine into a common function. This also helps so that
if a env var is defined with a trailing slash all will continue to
work as expected.
Fixes#100
Added the ability to fetch an alternative location for /proc via an
environment variable. If the env var is not set it will return /proc as
the default value.
/proc/meminfo reports memory in KiloBytes and so needs a multiplier of
1024 instead of 1000.
The kernel reports in terms of pages and the proc filesystem is left
shifting by 2 for 4KB pages to get KB. Since this is a binary shift,
Bytes will need to shift by 10 and so get multiplied by 1024.
From the kernel code. PAGE_SHIFT = 12 for 4KB pages
"MemTotal: %8lu kB\n", K(i.totalram)
Thanks to @subhachandrachandra!
Minje Park