From 869d43f1022be96dd16641bf29e1143b8d8d4dbd Mon Sep 17 00:00:00 2001
From: "Pawel \"l0ner\" Soltys" <pwslts@gmail.com>
Date: Fri, 13 Feb 2015 18:38:21 +0100
Subject: [PATCH] Fixed RAM usage calculation on FreeBSD - Instead of
 displaying hardware ram quantity, display ram available to be   allocated by
 applications. FreeBSD uses some ram for kernel, segment mappings   and other
 stuff. Those memory pages are not available for allocation by   applications.
 - Calculate correctly ram usage. Active + Wired (buffers). Nothing else.

For more info see:
- http://www.cyberciti.biz/files/scripts/freebsd-memory.pl.txt
- conky source code on github
- output of top and vmstat on FreeBSD
- http://www.zabbix.com/forum/showthread.php?t=21826
- https://support.zabbix.com/browse/ZBXNEXT-774

htop on FreeBSD uses linux procfs compatibility layer, and thus it's readings
are a little off.
---
 freebsd/memory.cc | 55 ++++++++++++++++++++++++++---------------------
 1 file changed, 31 insertions(+), 24 deletions(-)

diff --git a/freebsd/memory.cc b/freebsd/memory.cc
index aa3b076..4c3ce9c 100644
--- a/freebsd/memory.cc
+++ b/freebsd/memory.cc
@@ -31,40 +31,48 @@
 std::string mem_string( bool use_colors = false )
 {
   // These values are in bytes
-  int32_t total_mem = 0;
-  int64_t used_mem = 0;
-  int64_t unused_mem = 0;
-  int32_t inactive_mem = 0;
-  int32_t active_mem = 0;
-  int32_t free_mem = 0;
-  int32_t wired_mem = 0;
-  int32_t page_size = 0;
-  int32_t cache_mem = 0;
+  //u_int total;
+  //u_int free;
+  //u_int inactive;
+  //u_int cache;
+  u_int wired;
+  u_int active;
+  u_int page_size;
+  u_int page_count;
   std::ostringstream oss;
 
   // Get total physical memory, page size, and some other needed info
-  GETSYSCTL( "hw.realmem", total_mem );
+  // instead of using realmem which reports quantity of ram installed on
+  // platform, use physmem which reports ram available to system.
+  //GETSYSCTL( "hw.physmem", total );
   GETSYSCTL( "hw.pagesize", page_size );
+  // page count reflects actual size of memory we have available for
+  // applications. it will be less than realmem or physmem, since it doesn't
+  // include what's been allocated for kernel, but it will be equal to
+  // free + inactive + cache + wired + active, and thus will reflect better
+  // what's actually available.
+  GETSYSCTL( "vm.stats.vm.v_page_count", page_count );
 
-  GETSYSCTL( "vm.stats.vm.v_free_count", free_mem );
-  GETSYSCTL( "vm.stats.vm.v_inactive_count", inactive_mem );
-  GETSYSCTL( "vm.stats.vm.v_cache_count", cache_mem );
-  GETSYSCTL( "vm.stats.vm.v_wire_count", wired_mem );
-  GETSYSCTL( "vm.stats.vm.v_active_count", active_mem );
+  //GETSYSCTL( "vm.stats.vm.v_free_count", free );
+  //GETSYSCTL( "vm.stats.vm.v_inactive_count", inactive );
+  //GETSYSCTL( "vm.stats.vm.v_cache_count", cache );
+  GETSYSCTL( "vm.stats.vm.v_wire_count", wired ); // Buffers
+  GETSYSCTL( "vm.stats.vm.v_active_count", active );
 
-  // Get all memory which can be allocated
-  //unused_mem = (cache_mem + free_mem) * page_size;
-  used_mem = ( static_cast<int64_t>( active_mem ) + 
-      static_cast<int64_t>( inactive_mem ) + 
-      static_cast<int64_t>( wired_mem ) ) * static_cast<int64_t>( page_size );
+  // Get all memory which can be allocated, which on FreeBSD is:
+  // cached + inactive + free
+  //u_int unused = ( cache + inactive + free ) * page_size;
+
+  // Used memory on FreeBSD is active + wired.
+  u_int used = ( active + wired ) * page_size;
 
   if( use_colors )
   {
-    oss << mem_lut[( 100 * used_mem ) / total_mem];
+    oss << mem_lut[ ( 100 * used ) / ( page_count * page_size ) ];
   }
 
-  oss << convert_unit( used_mem, MEGABYTES ) << '/' 
-    << convert_unit( total_mem, MEGABYTES ) << "MB";
+  oss << convert_unit( used, MEGABYTES ) << '/'
+    << convert_unit( page_count * page_size, MEGABYTES ) << "MB";
 
   if( use_colors )
   {
@@ -73,4 +81,3 @@ std::string mem_string( bool use_colors = false )
 
   return oss.str();
 }
-