I use Threadripper 1920x, it has no integrated graphics. Motherboard is Gigabyte x399.
Free shows:
Mem: total 62G or 65909900
dmesg shows:
1329464K reserved
Which matches exactly the missing 1.1G.
It says it's reserved in BIOS-e820

How to reduce this BIOS reserved memory nonsense?
How much is reserved on your Ubuntu?

  • 2
    Please add output of free and free -h to the question. Maybe /1024 rounding issue. – N0rbert May 19 '19 at 19:01
  • answered in the main – Daniel May 20 '19 at 20:19

On my 8,000 MB system I'm missing 189 MB. Your system being 8 fold would extrapolate to 1,512 MB in comparison. Personally I wouldn't worry about missing 1,300 MB out of 64,000 MB. As @N0rbert suggests it could simply be a 1024 x 1024 x 1024 (GiB) vs 1000 x 1000 x 1000 (GB) issue.

That said there are ways to free up reserved memory: Reducing reserved RAM

The Linux Kernel goes through extraordinary steps to use RAM efficiently and to cache data and buffers. Even programs you've run once are kept in RAM as long as possible in case you run them a second time. My philosophy would be to let Linux manage the RAM unless a substantial percentage is missing.


I see a similar situation on my server:

$ free
              total        used        free      shared  buff/cache   available
Mem:       65907424      656828    64815756       64120      434840    63179300
Swap:        999420           0      999420

My guess is that this is due to running a 32-bit version of the OS, because when I boot it using a different GNU/Linux distribution, the 480 GB show up correctly.

uname -a shows i686 not x86_64.

$ uname -a
Linux computer 4.15.0-51-generic #55-Ubuntu SMP Wed May 15 14:26:28 UTC 2019 i686 athlon i686 GNU/Linux

(It also only detects 8 cores of the 48 installed, which is also detected correctly with a different OS).

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