HOWTO: Clear filesystem memory cache

[Anduu]

Hi guys! This doesn't seem to work in 10.04. I get

bash: /proc/sys/vm/drop_caches: Permission denied

I am not well versed in the terminal and have only been using linux for a couple of months now. I am using PAE with 6 gb of ram. Hope you guys can help. Oh, and the system monitor shows full memory cache use.

I had the same problem...even sudo wouldn't let me.

This worked however...

sudo su
echo 3 > /proc/sys/vm/drop_caches

[bhavin mehta]

Hi guys! This doesn't seem to work in 10.04. I get

bash: /proc/sys/vm/drop_caches: Permission denied

I am not well versed in the terminal and have only been using linux for a couple of months now. I am using PAE with 6 gb of ram. Hope you guys can help. Oh, and the system monitor shows full memory cache use.

sudo su
sync
echo 3 > /proc/sys/vm/drop_caches

[CylnZ]

Thanks, this worked a treat.

[darshana]

don't use

sudo

to run it as root. Log in to the system as root, then this works fine

sudo sync; echo 3 > /proc/sys/vm/drop_caches
[sudo] password for darshana:
bash: /proc/sys/vm/drop_caches: Permission denied

[petteriIII]

don't use

sudo

to run it as root. Log in to the system as root, then this works fine

I hate to 'sudo su' and it's ilk. I use:
sudo sync; echo 3 | sudo tee /proc/sys/vm/drop_caches

[lakosshoots]

sudo sh -c "sync; echo 3 > /proc/sys/vm/drop_caches"

this worked for me on 10.04. i used the memory system monitor and it went down right away

[Maxei]

I tried these proposed solutions in Lucid lynx. No errors displayed. But the System Monitor showed no changes after, and I am having 37% of used memory and swap history. Is that normal?

[Astrals]

sudo sh -c "sync; echo 3 > /proc/sys/vm/drop_caches"

this worked for me on 10.04. i used the memory system monitor and it went down right away

This worked great for me, thank you.

I have 8gb 800 corsair (4x2gb)
One of my issues with 10.04.
Fresh reboot and watch a video using the default totem movie player and after about an hour my cache went up to about 68% after an hour.
9.10 did not give me this issue with the same user setup profile.
Also my cache would go up even using firefox.
It seems to me the cache is not being cleared.
If anyone has an answer to why this happens and what the causes are please post it here and also pm me, i always want to understand and learn.
Thank you.

[guvnr]

that's cos ya need to be root ya crazyhorse

sudo su root
sync
blah or whatever can't remember but it worked now it's a bash alias, thank you Sir.

[psusi]

As someone already mentioned, drop_caches is perfectly safe, there is no risk of data loss, however, the ONLY reason to do this is because you are doing performance benchmarking and want to time how long it takes to read something with a cold cache.

This worked great for me, thank you.

I have 8gb 800 corsair (4x2gb)
One of my issues with 10.04.
Fresh reboot and watch a video using the default totem movie player and after about an hour my cache went up to about 68% after an hour.
9.10 did not give me this issue with the same user setup profile.
Also my cache would go up even using firefox.
It seems to me the cache is not being cleared.
If anyone has an answer to why this happens and what the causes are please post it here and also pm me, i always want to understand and learn.
Thank you.

That is SUPPOSED to happen. The cache is not supposed to be cleared. It is supposed to use all of your free ram to cache data you have accessed in case you need it again.

that's cos ya need to be root ya crazyhorse

sudo su root
sync
blah or whatever can't remember but it worked now it's a bash alias, thank you Sir.

Use sudo -s instead of sudo su.