I'm running Linux Mint 20. I often encounter low memory situations. Today I do not understand why available is so low. As per What is the meaning of `shared` memory in the `free` command? shared is sum of tmpfs systems, but my sum is times less.
free -hw
total used free shared buffers cache available
Mem: 15Gi 6,2Gi 4,6Gi 3,9Gi 26Mi 4,5Gi 5,0Gi
Swap: 0B 0B 0B
free -h
total used free shared buff/cache available
Mem: 15Gi 5,9Gi 5,1Gi 3,7Gi 4,4Gi 5,4Gi
Swap: 0B 0B 0B
df -h
Filesystem Size Used Avail Use% Mounted on
udev 7,7G 0 7,7G 0% /dev
tmpfs 1,6G 1,7M 1,6G 1% /run
tmpfs 7,7G 254M 7,5G 4% /dev/shm
tmpfs 5,0M 4,0K 5,0M 1% /run/lock
tmpfs 7,7G 0 7,7G 0% /sys/fs/cgroup
cache 786M 247M 540M 32% /home/alex/.cache
cache 158M 0 158M 0% /home/root/.cache
rd 16G 460M 15G 3% /media/ramdrive
tmpfs 1,6G 176K 1,6G 1% /run/user/1000
rd is tpmfs and cache(s) are also tmpfs for performance/low disk wearout, still it is ~1Gb total in used, not 3.7. Also why cache per free can be so high? (I've just dropped caches).
ADDED: right after I posted the question I decided to add free -hw and shared grew by 0.2Gb while df output stayed the same.
ADDED 2: In https://linoxide.com/command-to-show-shared-memory-settings/ it is shown to use ipcs command to show shared memory. In my case the sum is ~880Mb. How does it correspond to /proc/meminfo Shmem (it is same as free outputs) and info on tmpfs systems? The sum from ipcs does not look like any number produced by those. I was not able to find answer by web search.
