I Installed Ubuntu 20.04 some days ago, on a system with a 500GB SSD and 16GB of ram. It runs incredibely fast. I used mainly for web development with docker and 2 browsers opened.
After 2 - 3 days using it notice that sometimes, after have used it for a few hours it suddendly froze for many minutes, sometimes it recover normallity but others i have to press the RESET button.
Looking into this, it seems like the swap is being used, more and more until is filled completely, and I"ve notice that each time it froze, swap is 100% used, with 0 bytes left.
Initially it was a 2GB /swapfile I increase it to 8GB,
free -hm
total used free shared buff/cache available
Mem: 15Gi 13Gi 405Mi 102Mi 1.3Gi 1.1Gi
Swap: 8.0Gi 8.0Gi 21Mi
$ vmstat 1
procs -----------memory---------- ---swap-- -----io---- -system-- ------cpu-----
r b swpd free buff cache si so bi bo in cs us sy id wa st
1 0 8184072 1159480 106780 1429920 30 68 264 161 79 37 18 6 76 0 0
0 0 8184072 1160328 106788 1430064 20 0 104 164 2386 7913 17 6 77 0 0
2 0 8184072 1101808 106796 1430072 76 0 76 56 2266 7488 16 6 77 0 0
0 0 8184072 1159684 106804 1415396 28 0 28 224 2456 8942 18 7 76 0 0
0 0 8184072 1148108 106804 1415468 16 0 24 0 2395 8012 20 6 75 0 0
0 0 8184072 1162416 106868 1415628 0 0 8 10032 2627 8865 27 6 66 1 0
1 0 8184072 1213260 106868 1415632 0 0 0 0 3677 7461 18 8 74 0 0
0 0 8184072 1218236 106868 1415656 108 0 132 0 2287 7940 14 5 82 0 0
0 0 8183816 1216772 106868 1415644 252 0 300 0 2742 9758 24 5 71 0 0
0 0 8183816 1216968 106896 1415776 12 0 16 752 2300 8125 16 6 78 0 0
0 1 8178440 1159532 106912 1434828 6844 0 16772 0 6270 19751 35 8 56 1 0
2 0 8168200 1030912 107140 1441496 12480 0 18668 216 14645 19022 60 11 28 1 0
1 0 8166408 979080 107140 1443392 2040 0 3860 0 7176 12398 56 6 38 0 0
2 0 8165896 970196 107156 1443220 644 0 644 408 11478 10704 56 5 39 0 0
1 0 8165896 974404 107172 1441176 72 0 72 216 4232 11306 41 5 54 0 0
1 0 8165384 1013824 107172 1431864 564 0 564 0 9214 12768 38 8 54 0 0
5 0 8164104 876940 107176 1440800 1500 0 1620 608 9258 20153 48 7 45 0 0
4 0 8164104 742736 107192 1440848 272 0 272 224 7449 12620 56 5 38 0 0
7 0 8164104 926696 107232 1440640 292 0 292 3076 6702 14253 44 8 48 0 0
2 0 8162824 899408 107232 1440764 2052 0 2056 0 4738 12986 38 6 56 0 0
2 0 8161800 886416 107232 1440956 912 0 1092 0 11952 17109 39 7 54 0 0
top - 06:29:52 up 16:09, 2 users, load average: 1.35, 1.87, 1.75
Tasks: 426 total, 2 running, 420 sleeping, 0 stopped, 4 zombie
%Cpu(s): 24.7 us, 4.5 sy, 0.0 ni, 70.7 id, 0.1 wa, 0.0 hi, 0.0 si, 0.0 st
MiB Mem : 15965.7 total, 714.1 free, 13738.2 used, 1513.3 buff/cache
MiB Swap: 8192.0 total, 227.5 free, 7964.5 used. 1616.1 avail Mem
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
5238 nh 20 0 11.5g 1.5g 117064 R 60.5 9.6 137:21.61 firefox
64514 nh 20 0 621592 27624 22176 S 11.8 0.2 84:53.46 youtube-music-d
64528 nh 20 0 9278472 112372 20812 S 6.8 0.7 59:40.88 youtube-music-d
64577 nh 20 0 4724728 7068 4712 S 5.2 0.0 36:57.94 youtube-music-d
64283 nh 20 0 4927544 46564 15200 S 4.1 0.3 31:13.02 youtube-music-d
5341 nh 20 0 6486452 2.2g 59748 S 3.9 14.3 73:51.02 Web Content
15675 nh 20 0 3112492 322920 41744 S 3.9 2.0 36:20.51 Web Content
135808 nh 20 0 36.5g 202720 103396 S 2.8 1.2 0:09.46 chrome
I also modified some somethings on the /etc/sysctl.conf:
vm.swappiness=5
vm.min_free_kbytes=240000
This settings are new (including the 8Gb size) and it has not frozen yet, but I noticed that is again almost used 100%. I will update if it frozes again :_)
firefox(11.5g virtual, 60.5%CPU) andchrome(36.5g virtual, 2.8%CPU) are trying for unchecked growth. Swap space is not allocated on its own, it's allocated based on virtual memory usage.