For me, it would be necessary, if you’re running Qubes with 4-8GB of RAM. But with 16,32 or even 64 GB of RAM a swap partition may be useless…
For me, it would be necessary, if you're running Qubes with 4-8GB of RAM. But with 16,32 or even 64 GB of RAM a swap partition may be useless...
What about the "swappiness" kernel parameter? Here I see vm.swappiness=60 (default)
Having 16GB RAM and only 5 VMs running, no paging happened, even after I had set swappiness to 90 in Dom0:
[root@dom0 master]# free
total used free shared buff/cache available
Mem: 3962388 817404 2410848 13412 734136 2950516
Swap: 10485756 0 10485756
According to https://linuxhint.com/understanding_vm_swappiness/:
* 0: swap is disable
* 1: minimum amount of swapping without disabling it entirely
* 10: recommended value to improve performance when sufficient memory exists in a system
* 100: aggressive swapping
So I even set swappiness to 100, just top see what happens, and I still did not see any paging.
Even when starting three additional VMs, I could not see paging in Dom0:
[root@dom0 master]# vmstat 5
procs -----------memory---------- ---swap-- -----io---- -system-- ------cpu-----
r b swpd free buff cache si so bi bo in cs us sy id wa st
0 0 0 2406852 55696 681864 0 0 272 331 1101 1033 1 1 97 0 1
0 0 0 2406592 55696 681932 0 0 26 198 5320 5075 1 1 97 0 1
0 0 0 2406576 55704 681940 0 0 13 103 5164 4973 1 1 97 0 1
0 0 0 2406624 55704 681860 0 0 13 122 5217 5015 1 1 97 0 1
0 0 0 2405616 55708 681876 0 0 13 139 7042 6530 1 1 96 0 1
0 0 0 2406144 55716 681888 0 0 38 283 7819 7319 2 1 95 0 2
1 0 0 2408128 55716 681924 0 0 1 118 7081 6661 1 1 96 0 1
1 0 0 2291836 55836 682396 0 0 79 366 8030 7576 7 6 83 0 3
0 0 0 2388740 54800 692632 0 0 20717 2839 14237 12176 4 5 81 0 9
3 0 0 2268800 54916 694556 0 0 72948 6978 22038 21880 7 10 69 0 14
1 0 0 2332968 54916 704920 0 0 12738 12858 13951 12536 6 6 71 0 17
2 0 0 2259164 56068 706068 0 0 12377 5766 13037 12304 10 9 64 1 17
1 0 0 2263504 55040 717512 0 0 47908 9822 17386 16391 3 6 75 0 15
3 0 0 1950336 55048 718884 0 0 50536 14435 20932 20627 4 6 69 1 21
0 0 0 1789084 55056 719504 0 0 22490 6858 12711 12202 2 3 84 0 10
0 0 0 1821772 55064 719532 0 0 275 433 6988 6579 3 2 93 0 2
1 0 0 1814452 55072 719496 0 0 230 918 5477 5370 1 1 94 0 3
0 0 0 1712640 55080 719660 0 0 4551 18286 8909 8085 2 3 86 0 9
0 0 0 2131492 56152 709116 0 0 1826 5031 10883 9946 5 8 72 3 12
4 0 0 2259808 56164 698804 0 0 1322 7122 9417 8659 2 3 88 0 6
0 0 0 2333696 56224 698156 0 0 1862 2295 9031 8399 4 8 76 4 7
0 0 0 2362572 56284 686708 0 0 676 1020 7809 7022 4 8 75 7 5
0 0 0 2383836 56296 686484 0 0 13 374 5142 4777 2 1 96 0 1
0 0 0 2384740 56304 686464 0 0 0 218 5131 4880 1 1 97 0 1
0 0 0 2385496 56304 686372 0 0 0 124 4637 4471 1 1 97 0 1
^C
Regards,
Ulrich