linux tmpfs

tmpfs is a special file system used in Linux. Not like other traditional disk/partition based file systems, it store’s the file in memory. So it is much quicker than normal file system.

Then how can we use tmpfs? Well, we will just mount it as below:

#mount tmpfs –t tmpfs /var/tmp

Usually we can just add a size parameter to set the maximane size as

mount tmpfs -t tmpfs /var/tmp -o size=100m

we can do some test to write a 50M file there, then we can check the used memory increased, then we delete the file and the memory is freed

root@mysql:~# free -m

             total       used       free     shared    buffers     cached

Mem:          7985        290       7694          0         17        115

-/+ buffers/cache:        156       7828

Swap:         8187          0       8187

root@mysql:~# dd if=/dev/zero of=/var/tmp/zero.txt count=100000

100000+0 records in

100000+0 records out

51200000 bytes (51 MB) copied, 0.198847 s, 257 MB/s

root@mysql:~# free -m

             total       used       free     shared    buffers     cached

Mem:          7985        339       7646         49         17        164

-/+ buffers/cache:        156       7828

Swap:         8187          0       8187

root@mysql:~# rm /var/tmp/zero.txt

root@mysql:~# free -m

             total       used       free     shared    buffers     cached

Mem:          7985        290       7694          0         17        115

-/+ buffers/cache:        157       7827

Swap:         8187          0       8187