LP #1641635: pt-summary reports wrong memory size

User impact:

• Data about memory provided by pt-summary are not reliable and this complicates and confuses troubleshooting 

Original reports:

**Reported in Launchpad by Tibor Korocz last update 22-11-2016 19:38:12

Hi,

On a server with 256G memory pt-summary reports 2.5G of memory. See results below:

1. free -m
   total used free shared buffers cached
   Mem: 258207 256696 1510 383 463 32271
   -/+ buffers/cache: 223961 34245
   Swap: 16383 39 16344

1. free -mh
   total used free shared buffers cached
   Mem: 252G 251G 1.0G 505M 463M 31G
   -/+ buffers/cache: 218G 33G
   Swap: 15G 39M 15G

1. cat /proc/meminfo
   MemTotal: 264404376 kB
   MemFree: 1231712 kB
   Buffers: 474832 kB
   Cached: 33537260 kB
   SwapCached: 2824 kB
   Active: 225141140 kB
   Inactive: 34971456 kB

Pt-summary:

1. Memory #####################################################
   Total | 2.5G
   Free | 1.7G
   Used | physical = 2.5G, swap allocated = 1.6G, swap used = 39.9M, virtual = 2.5G
   Shared | 244.0k
   Buffers | 436.0M
   Caches | 3.1G

Checking the code :
https://github.com/percona/percona-toolkit/blob/2.2/bin/pt-summary#L1171

We can see pt-summary use `free -b`:

free -b
total used free shared buffers cached
Mem: 2707500810 2700511313 698949632 233472 486223872 3480769740
-/+ buffers/cache: 2347572101 3599287091
Swap: 1717986508 41594880 1713827020

And here we are:

2707500810 bytes is 2.5G.

Not sure this is a bug in the tool or not, but we might can check `meminfo`
results also and if they are not the same, show a warning or something.

Thanks,
Tibi