Fix wrong physical memory

[vlatan]

Closes #779

The variable $physical_memory is correctly assigned from forcemem and converted to bytes early in sub os_setup (line 523).

$physical_memory = $opt{'forcemem'} * 1048576;

But then on line 598 it is reassigned (overwritten) from a forcemem value, if existing, without converting it to bytes.

$physical_memory=$opt{forcemem} if (defined($opt{forcemem}) and $opt{forcemem} gt 0);

This leads to a problem when converted/rounded back to KB, MB or GB in hr_bytes. Now because of the reassignment $physical_memory has the MB value, but hr_bytes treats that value as bytes.

$result{'OS'}{'Physical Memory'}{'pretty'} = hr_bytes($physical_memory);

This will lead to incorrectly determining the Physical memory. For example if a user passes --forcemem 2000, the hr_bytes will convert that to 2.0K, thinking 2000 is bytes, and the result in the console will be:

[--] Physical Memory: 2.0K

And ultimately because of this, mysqltuner will give wrong suggestions about the memory consumption:

*** MySQL's maximum memory usage is dangerously high ***
*** Add RAM before increasing MySQL buffer variables ***

[jmrenouard]

Thanks @vlatan