My desktop PC has been quite sluggish lately, especially after I leave it overnight and then start using it again the next morning. I've tried decreasing swappiness (current value is 5) and the disk activity is now less intense. But the sluggishness remains. vmstat 1 output is something like:
procs -----------------------memory---------------------- ---swap-- -----io---- -system-- --------cpu--------
r b swpd free buff cache si so bi bo in cs us sy id wa st
2 0 1214672 1325428 100660 2065148 0 0 0 0 793 3396 7 2 92 0 0
3 0 1214672 1329396 100660 2067812 0 0 0 0 916 5294 9 1 90 0 0
2 0 1214672 1330884 100660 2065156 0 0 0 0 756 3759 4 2 93 0 0
2 0 1214672 1320344 100676 2065260 0 0 0 3056 764 4351 8 2 89 1 0
0 0 1214672 1328776 100676 2065260 0 0 0 0 850 4005 3 1 95 0 0
0 0 1214672 1331256 100676 2065260 0 0 0 0 890 4519 5 3 92 0 0
0 0 1214672 1324560 100676 2067920 0 0 0 52 674 3485 6 2 93 0 0
2 0 1214672 1322080 100676 2065260 0 0 16 0 874 5058 9 3 88 0 0
0 0 1214672 1323816 100684 2065364 0 0 44 1740 1453 16016 8 4 88 0 0
Hundreds and sometimes thousands of interrupts, tens of thousands even >100k context switches are often encountered. Merely moving mouse pointer around rather quickly will make the context switches shoot to the roof, especially if I point the mouse to the Task Manager area in the panel. I'm using KDE Plasma (KDE Frameworks 5.35.0, Linux Mint 18.2).
If I use another desktop environment like Cinnamon, the context switches numbers are not nearly as high (usually mid-hundreds when idle, or around 1000-2000 when more active). But I prefer Plasma to other desktop environments.
How to find out the cause of the problem in more details and remedy it?
