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Re: using swap when there is free ram




On Fri, Mar 01, 2019 at 07:34:50PM +0100, Pascal Hambourg wrote:
> Le 01/03/2019 à 18:56, Reco a écrit :
> > 
> > First, there's huge amount of unused (not to be confused with "free")
> > memory on your host. And no, it's not a filesystem's cache (600M), it's
> > really "nothing there"-unused memory which amounts 1880M.
> 
> This is the amount reported in /proc/meminfo as MemFree - not MemUnused.
> Can you please explain your definitions of "free" and "unused" memory ?

Documentation/filesystems/proc.txt.gz

What they call "free memory" usually is called MemAvailable in
/proc/meminfo.

"MemFree", which was the sum of "LowFree" and "HighFree" back in the day
(and still is for some architectures) - is the amount of memory which
isn't used for anything, hence the "unused".


> > Taking it all into the account, I propose the following scenario - not a
> > long time ago there was a process (or a couple of those). Was it the
> > browser, or something written in Java (or Python), or some kind of
> > Virtual Machine - is not relevant, but it did consume RAM. But it got
> > terminated, and what we're seeing here is the aftermath.
> 
> Another scenario : at some point the pagecache (file cache) grew much
> bigger due to massive file read/write operation, then the files were
> deleted or the filesystem was unmounted and the file cache pages were
> freed.

I agree that's another possibility.

Reco