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Old 06-11-2020, 12:40 PM   #1
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in order to release memory i execute
echo 3 >/proc/sys/vm/drop_caches.

this mean that the kernes sees that the value of drop_caches =3 and start to free memory?
is there any other command to free more memory?
Old 06-11-2020, 04:47 PM   #2
Registered: Jun 2020
Distribution: Xubuntu / Slackware
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Not to be snarky, but 'close some applications' would free up memory (and/or switch to lower-resource-requirement versions of applications - a 'big' example would be switching DEs from GNOME or KDE to XFCE or Blackbox). I know I've seen some applications (web browsers seem to be the worst, but I've observed this with office suites and some games too) that can take up quite a bit of memory (into the realm of a few GiB) even with 'nothing open' due to their own inner workings. Closing and restarting the browser/app and/or clearing its cache/storage can sometimes help there, but perhaps this doesn't apply to your situation (I'm admittedly guessing at your use-case here).

AFAIK - Dropping the cache doesn't really 'free' memory, from what I understand the OS can still send applications into that memory, but it otherwise uses it for caching (rather than let it sit empty/untouched) to improve performance. It shouldn't get in the way of an application needing memory. I found this website useful: (if you scroll down to the bottom they also link to a second page that has some examples with the cache).
Old 06-12-2020, 10:35 AM   #3
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then is there a situation when is necessary to echo 3 >/proc/sys/vm/drop_caches?
Old 06-12-2020, 02:43 PM   #4
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As I recall I read that 3 should never be used in a production machine. 1 is recommended. 3 is nuclear.
Old 06-12-2020, 03:06 PM   #5
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I once used that for the broken Suse 10 kernel 2.6.16 to avoid oom killer during long lasting heavy i/o.
Never since.


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