Swappiness Recommendations?

Installing and Using OpenWrt
1

I've been using LEDE for the past month on my WRT1900ACS and happy about the switch from another firmware project. Everything has been really stable, linux, wifi performance and all of the extra packages. I'm now trying to fine tune overall performance.

Extroot is setup and using a high quality USB3 flash drive with ware leveling. The disk has two partition; the first a 1GB swap, and the second about 30GB for rootfs (overlays).

Would you recommend adjusting swappinessl? The stable relese 17.01.1 defaults to swappiness=60 (at least) on the WRT1900ACS.

I noticed a few times that my system was using about 100mb of swap while my Mac was using the Time Machine server (Netatalk and Avahi) on this device.

I'd love to hear others opinions or thoughts on the matter.

The link below is a pretty good start for anyone wanting to learn about swappiness. https://en.wikipedia.org/wiki/Swappiness

Regards

-Mrengles

2

Do you really need swap????
I doubt that you will get much advice about swap as it is probably used very rarely.

1 Like
3

I would not use swap either, but you can free up some RAM by mounting /tmp on the USB stick as this page suggests https://wiki.openwrt.org/doc/uci/fstab

4

Thanks @hnyman @fantom-x

I'm not really sure if swap is needed., havent tried without.

I'll give it a shot for a little while and report back. I'll so ready about mounting /tmp to /dev/sda1 (USB).

5

This look to me like someone with a solution looking for a problem... :wink:

That device of your has RAM enough to run most "normal" workloads without swap; adding a bit of swap will hurt nobody, so go for it. Now, tuning the kernel parameters are major words, something I would only after facing a problem, never before.

6

@Mrengles Sir, with that BEAST of a router, you don't need to use swapping... I think that would hurt more than it would help... let the beast manage the memory by itself. If you saw it using 100MB with TimeMachine, that's ok, as the device has 512MB and 100MB is A LOT for normal operations... but would be a very rare ocassion.

Just my 2 cents.

7

Thanks everyone! I've read every reply and have decided to disable swap and test results. I can always re-enable if needed.

Far as snappiness goes, I'll do the same, fiddle if needed, but first let the kernel decide for a while.

Thanks again!