vm.swappiness

Magnus Kessler mkessler at basho.com
Tue Feb 2 04:17:13 EST 2016


On 29 January 2016 at 18:26, Sakoulas, Byron <
ByronSakoulas at catholichealth.net> wrote:

> Is it possible that Basho’s recommendation on vm.swappiness is out of date?
>
> The current recommendation (per
> http://docs.basho.com/riak/latest/ops/tuning/linux/) is still to set
> vm.swappiness to 0.
>
> Based on
> https://www.percona.com/blog/2014/04/28/oom-relation-vm-swappiness0-new-kernel/
> it appears that in kernel 3.5 and up, the behavior of vm.swappiness=0 was
> changed.
>
> Due to that, should we modify our vm.swappiness to 1?
>
> Thanks
>
>
Hi Byron,

Yes, you are correct. If you want to keep the swapping behaviour prior to
Linux 3.5 (minimum amount of swapping without disabling it entirely) on
Linux 3.5+, you should use vm.swappiness=1.

I will make sure that the documentation is updated to reflect this.

Generally we recommend to turn swapping off to avoid long unpredictable
latencies when the kernel starts to swap out memory. Regardless of which
setting you use, please check the behaviour of your system under high
memory load.

Regards,

Magnus

-- 
Magnus Kessler
Client Services Engineer
Basho Technologies Limited

Registered Office - 8 Lincoln’s Inn Fields London WC2A 3BP Reg 07970431
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