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From: "Valdis Klētnieks" <valdis.kletnieks@vt.edu>
To: Neel chakraborty <neelroboinfo365@gmail.com>
Cc: kernelnewbies@kernelnewbies.org
Subject: Re: Free RAM in Linux .
Date: Tue, 17 Dec 2019 01:29:33 -0500	[thread overview]
Message-ID: <183371.1576564173@turing-police> (raw)
In-Reply-To: <CAENbuEoY6T8uh2t7f2DgF_ws9H93k03EKYcLZnWbOPRKEeJgpg@mail.gmail.com>


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On Tue, 17 Dec 2019 10:39:08 +0530, Neel chakraborty said:

> Does Linux use all of the physical memory (RAM) I have ? In both the
> outputs of /proc/meminfo and free -h , shows that 1.4 gigs is used and 1.6
> gigs is cached , and the rest is "free" out of 32 Gigs . The available ram
> is the cached ram + reclaimable ram + free ram , right ?

That probably means that the processes you have running use a total
of 1.4G of ram, and you've referenced 1.6G of files on disk.

The rest is free because you've not done anything to give the system even
a hint of what to do with the other 27G of RAM.

If you reference a whole bunch of files (find /usr -type f | xargs cat) > /dev/null
or other similar), you'll see more gigs used for cache.

If you run a few large processes, like a Chrome with 90 tabs open, you'll
see the other number go up.

> And also , does the linux kernel use the amount of ram which is not used by
> applications as paging cache ? Say I have 4 gigs of ram , and Firefox is
> using 1 gig of it , the rest of RAM is used for disk/page caching or is it
> just unused and left there ?

The kernel itself will use some of it, other processes will use some of it, and
if there's any left, it will be used for disk caching - but not until a process
has actually referenced data off the disk.

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      reply	other threads:[~2019-12-17  6:30 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-17  5:09 Free RAM in Linux Neel chakraborty
2019-12-17  6:29 ` Valdis Klētnieks [this message]

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