Arch Linux

tgc

Member

From: DK

Registered: 2004-03-09

Posts: 96

Resizing /dev/shm

Hi!

I been wondering a bit about the size of /dev/shm
As far as i can see it's half the size of my physical RAM, which means it's around 60 MB. But how big is /dev/shm supposed to be? I google around a bit, and some places it's recommend to set it to be at least the size of the physical RAM.
Any thoughts or recommandations?

BTW, i've removed the tmpfs for /tmp since it also took half the RAM, but 60 MB wasen't allways enough...

i3839

Member

Registered: 2004-02-04

Posts: 1,185

Re: Resizing /dev/shm

/dev/shm isn't used that often, it's only used for posix shared memory. So most times it's zero Mb big. The size given is the max size, but if that is never reached then it doesn't matter what it is. If the default max size isn't big enough for certain app then you may need to increase it, although more likely you have bigger memory shortages elsewere in that case. If not, then it depends on the app using it.

tgc

Member

From: DK

Registered: 2004-03-09

Posts: 96

Re: Resizing /dev/shm

So that means that even though it claims to be using 60 MB, it doesn't actually use/lock the memory until needed?

luisfelipe

Member

Registered: 2004-05-06

Posts: 96

Re: Resizing /dev/shm

yes, that's basically the definition of a tmpfs.

Try looking it up in google or wikipedia for more detailed information.

i3839

Member

Registered: 2004-02-04

Posts: 1,185

Re: Resizing /dev/shm

To see how much it really uses use df:

$ df -h /dev/shm
Filesystem            Size  Used Avail Use% Mounted on
none                  126M     0  126M   0% /dev/shm