I upgraded from 14.04 to 16.04, and every time my machine starts using the swap space, it gets brutally slow, which did not happen with 14.04 even when using up to 90% of my swap space. I routinely see UI pauses of 30 seconds or more, and when the UI starts updating again, I see IO wait taking up all of the height on my system monitor stacked area graph. (Because it is IO wait, I wonder if this is a kernel-space issue, rather than a user-space one.)
My swap volume is on an LVM volume group with two SSDs. It is encrypted with LUKS.
I have tried:
- Changing swappiness from 60 to 10, then rebooting
- poking around in
/var/logto find anything that's saying what's going on. - Changing
/etc/fstabto use the UUID of the swap partition insudo blkid, following https://askubuntu.com/a/809350/487023
None of these changed the behavior in any way I could see.
Some odd things:
system-config-lvmshows no volume groups, even when launched withsudo.pvs,pvdisplay,lvmdiskscan -lall show no physical volumes. Maybe because of LUKS?- In 14.04, at boot-time, I would have to enter two passwords: one for the LUKS encryption of the logical volume containing
/home/, and the other for the LUKS encryption of the logical volume used as swap. Now, in 16.04, I only have to enter the password for the logical volume containinghome. - I have another computer at work with a similar setup that does not exhibit this bad behavior.
That machine was a fresh 16.04 install, though, rather than an upgrade.That machine was also an upgrade job.
How can I bring system performance back to where it was with 14.04 without buying a new computer or downgrading to 14.04? Is this a problem I can fix by changing a config file?
