Re: That greedy Linux VM cache

From: Austin S. Hemmelgarn
Date: Fri Jan 31 2014 - 11:58:06 EST




On 01/31/2014 09:47 AM, Igor Podlesny wrote:
> On 31 January 2014 00:58, Igor Podlesny <for.poige+linux@xxxxxxxxx> wrote:
> [...]
>> While I'm thinking about moving system back to XFS...
>
> Well, it helped just a bit. The whole picture remains, so it's not
> Btrfs' issue, but seemingly Linux VM's one. The problem can be briefly
> described as "if allowed to swap (swappiness != 0), VM would rather
> start swapping, than reduce cache size which holds ~ 25 % of RAM".
> Even more briefly it's stated in the Subject.
>
> From user's point of view, it looks like the system is being
> heavily swapped (and can be easily misinterpreted as it), but actually
> the most disk activity is permanent _reading_ from filesystem, and not
> accessing swap device.
>
> Should I fill in a bug report in kernel's bugzilla, or just upgrade
> the notebook? )
>
If I remember correctly, there is a sysctl for configuring how
aggressively the system tries to retain the VFS cache, changing the
value there might improve things for you.
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