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Knowing how to clear unused RAM in *nix is very useful. This quick guide will show you the commands needed to clear unused memory in all flavors of Linux.
NOTE: WE HIGHLY RECOMMEND USING [ICODE]sync[/ICODE] before doing this to ensure that dirty objects are freeable. Otherwise, running these commands may not yield the full benefit.
Debian, Ubuntu, and any other aptitude-based distribution:
To clear caches, simply run this in Terminal:
[ICODE]sudo sysctl -w vm.drop_caches=3[/ICODE]
To fully clear unused memory (page cache, inodes, and dentries), run this in Terminal:
[ICODE]sudo sync && echo 3 | sudo tee /proc/sys/vm/drop_caches[/ICODE]
Fedora, CentOS, and any other yum-based distribution:
To clear only the pagecache, do this in the Terminal:
[ICODE]echo 1 > /proc/sys/vm/drop_caches[/ICODE]
To clear dentries and inodes from memory, run this in Terminal:
[ICODE]echo 2 > /proc/sys/vm/drop_caches[/ICODE]
To clear everything, including the pagecache, dentries and inodes, run this in Terminal:
[ICODE]echo 3 > /proc/sys/vm/drop_caches[/ICODE]
NOTE: WE HIGHLY RECOMMEND USING [ICODE]sync[/ICODE] before doing this to ensure that dirty objects are freeable. Otherwise, running these commands may not yield the full benefit.
Debian, Ubuntu, and any other aptitude-based distribution:
To clear caches, simply run this in Terminal:
[ICODE]sudo sysctl -w vm.drop_caches=3[/ICODE]
To fully clear unused memory (page cache, inodes, and dentries), run this in Terminal:
[ICODE]sudo sync && echo 3 | sudo tee /proc/sys/vm/drop_caches[/ICODE]
Fedora, CentOS, and any other yum-based distribution:
To clear only the pagecache, do this in the Terminal:
[ICODE]echo 1 > /proc/sys/vm/drop_caches[/ICODE]
To clear dentries and inodes from memory, run this in Terminal:
[ICODE]echo 2 > /proc/sys/vm/drop_caches[/ICODE]
To clear everything, including the pagecache, dentries and inodes, run this in Terminal:
[ICODE]echo 3 > /proc/sys/vm/drop_caches[/ICODE]