From 89255b32a405d2551ae368d426e31bfb8013ab68 Mon Sep 17 00:00:00 2001
From: Sunggon Song <sunggon.song@quantil.com>
Date: Wed, 22 Jul 2020 12:56:17 +0900
Subject: [PATCH] Use the sum of MemFree, Cached, and Buffers as real available
 memory to improve the absence of MemAvailable field in old linux kernel
 version(prior to 3.14) or to improve the incorrect MemAvailable in docker
 containers. This PR solves issue #376

---
 src/tsung_controller/ts_os_mon_erlang.erl | 24 +++++------------------
 1 file changed, 5 insertions(+), 19 deletions(-)

diff --git a/src/tsung_controller/ts_os_mon_erlang.erl b/src/tsung_controller/ts_os_mon_erlang.erl
index 1f3e30d9d..da02ab4e9 100644
--- a/src/tsung_controller/ts_os_mon_erlang.erl
+++ b/src/tsung_controller/ts_os_mon_erlang.erl
@@ -262,25 +262,11 @@ get_os_data(DataName) -> get_os_data(DataName,os:type()).
 %% Use the result of the free commands on Linux and os_mon on all
 %% other platforms
 get_os_data(freemem, {unix, linux}) ->
-    case file:open("/proc/meminfo",[raw,read]) of
-        {ok, FD} ->
-            file:read_line(FD), % skip  MemTotal
-            {ok, Data} = file:read_line(FD),
-            ["MemFree:",RawFree,_] = string:tokens(Data," \n"),
-            case file:read_line(FD) of
-                {ok, "MemAvailable:" ++Tail} ->
-                    [Avail,_] = string:tokens(Tail," \n"),
-                    file:close(FD),
-                    list_to_integer(Avail)/1024;
-                {ok, NextLine} ->
-                    ["Buffers:",Buf,_] = string:tokens(NextLine," \n"),
-                    {ok, LastLine} = file:read_line(FD),
-                    ["Cached:",Cached,_] = string:tokens(LastLine," \n"),
-                    file:close(FD),
-                    (list_to_integer(RawFree)+list_to_integer(Buf) + list_to_integer(Cached)) / 1024
-            end;
-        _ ->
-            0
+    case os:cmd("awk '/^MemFree|^Cached|^Buffers/ {freemem+=$2} END {print freemem}' /proc/meminfo") of
+        "" -> 0;
+        Data ->
+            RealFreeMem = string:strip(Data, right, $\n),
+            list_to_integer(RealFreeMem) / 1024
     end;
 get_os_data(freemem, {unix, sunos}) ->
     Result = os:cmd("vmstat 1 2 | tail -1"),