Sar: Free memory statistics (including buffers, cache)

itemprop="text">

The
free commands gives the amount of free memory in two forms:
completely free memory (the Mem line) and disposable memory
used for caches and buffers (the -/+ buffers/cache
line):

-bash-3.2$ free
            -m
 total used free shared buffers cached
Mem: 16057 15173 884 0 17
            2520
-/+ buffers/cache: 12635 3422
Swap: 12287 4937
            7350

In this example,
there are 884 MB of free memory excluding buffers and cache, and 3422 MB of free memory
including buffers and cache.

How can
I get the second measurement (free memory, including buffers and cache) in
sar?

itemprop="text">

class="normal">Answer

The
-r flag for sar will give you kbmfree,
kbmemused, kbbuffers, and kbcached. It doesn't, unfortunately, total them like the -/+
buffers/cache column like the free command, so you will have to
pipe it through an awk or perl script to total them. Try
this:

sar -r |\
awk
            '
{
 if (NR > 3 && $3 != "kbmemfree" && $3 != "")
            {
 if ($1 != "Average:") {

 kbmemfree = $3

            kbmemused = $4
 kbbuffers = $6
 kbcached = $7

            }
 else {
 kbmemfree = $2
 kbmemused = $3

            kbbuffers = $5
 kbcached = $6

 }


            kbfree_plus_bufcache = kbmemfree + kbbuffers + kbcached
 kbused_minus_bufcache
            = kbmemused - kbbuffers - kbcached

 printf("%s %15d %15d\n", $0,
            kbfree_plus_bufcache, kbused_minus_bufcache)
 } else if ($3 == "kbmemfree")
            {
 printf("%s %15s %15s\n", $0, "kbfree+bufcache",
            "kbused-bufcache")
 } else {
 printf("%s\n",
            $0)

 }
}'