Arch Linux

XDarkAngelX

Member

Registered: 2014-01-08

Posts: 62

[SOLVED] Kernel swapping too aggressively seems to ignore vm.swappines

I am currently using the 4.16.8 kernel and Ever since using the 4.16 kernel the kernel started to swap too aggressively when my used memory hit the 5Gib mark(I have 8Gib ram).
The kernel will swap something like 2 Gib to the swap causing the computer to slow hard but previously I only incurred this kind of swapping when being close to the 7 Gib of used memory.
Another reason why I think this swapping is too aggressive as I had it start swapping the game(XCOM2) I was currently playing and shouldn't it swap old pages to the hard disk first?  just seem weird to me that it will swap the active process memory.
I tried reducing the vm.swappiness value to 10 from the default 60 but got the same exact behaviour also tried putting 0 and still same weird behaviour..
I also checked my logs and it the following errors seem to happen in the same time as the aggressive swapping :

מאי 16 15:50:50 Arch-Home kernel: radeon 0000:01:00.0: swiotlb buffer is full (sz: 2097152 bytes)
מאי 16 15:50:50 Arch-Home kernel: radeon 0000:01:00.0: swiotlb buffer is full (sz: 2097152 bytes)
מאי 16 15:50:50 Arch-Home kernel: radeon 0000:01:00.0: swiotlb buffer is full (sz: 2097152 bytes)
מאי 16 15:50:50 Arch-Home kernel: radeon 0000:01:00.0: swiotlb buffer is full (sz: 2097152 bytes)
מאי 16 15:50:51 Arch-Home kernel: radeon 0000:01:00.0: swiotlb buffer is full (sz: 2097152 bytes)
מאי 16 15:50:51 Arch-Home kernel: radeon 0000:01:00.0: swiotlb buffer is full (sz: 2097152 bytes)
מאי 16 15:50:51 Arch-Home kernel: radeon 0000:01:00.0: swiotlb buffer is full (sz: 2097152 bytes)
מאי 16 15:50:51 Arch-Home kernel: radeon 0000:01:00.0: swiotlb buffer is full (sz: 2097152 bytes)
מאי 16 15:50:51 Arch-Home kernel: radeon 0000:01:00.0: swiotlb buffer is full (sz: 2097152 bytes)
מאי 16 15:50:51 Arch-Home kernel: radeon 0000:01:00.0: swiotlb buffer is full (sz: 2097152 bytes)
מאי 16 15:50:56 Arch-Home kernel: swiotlb_tbl_map_single: 13 callbacks suppressed
מאי 16 15:50:56 Arch-Home kernel: radeon 0000:01:00.0: swiotlb buffer is full (sz: 2097152 bytes)
מאי 16 15:50:56 Arch-Home kernel: radeon 0000:01:00.0: swiotlb buffer is full (sz: 2097152 bytes)
מאי 16 15:50:56 Arch-Home kernel: radeon 0000:01:00.0: swiotlb buffer is full (sz: 2097152 bytes)
מאי 16 15:50:57 Arch-Home kernel: radeon 0000:01:00.0: swiotlb buffer is full (sz: 2097152 bytes)
מאי 16 15:50:58 Arch-Home kernel: radeon 0000:01:00.0: swiotlb buffer is full (sz: 2097152 bytes)
מאי 16 15:50:58 Arch-Home kernel: radeon 0000:01:00.0: swiotlb buffer is full (sz: 2097152 bytes)
מאי 16 15:50:59 Arch-Home kernel: radeon 0000:01:00.0: swiotlb buffer is full (sz: 2097152 bytes)
מאי 16 15:50:59 Arch-Home kernel: radeon 0000:01:00.0: swiotlb buffer is full (sz: 2097152 bytes)
מאי 16 15:51:00 Arch-Home kernel: radeon 0000:01:00.0: swiotlb buffer is full (sz: 2097152 bytes)
מאי 16 15:51:00 Arch-Home kernel: radeon 0000:01:00.0: swiotlb buffer is full (sz: 2097152 bytes)
מאי 16 15:51:36 Arch-Home kernel: swiotlb_tbl_map_single: 16 callbacks suppressed
מאי 16 15:51:36 Arch-Home kernel: radeon 0000:01:00.0: swiotlb buffer is full (sz: 2097152 bytes)
מאי 16 15:51:37 Arch-Home kernel: radeon 0000:01:00.0: swiotlb buffer is full (sz: 2097152 bytes)
מאי 16 15:51:37 Arch-Home kernel: radeon 0000:01:00.0: swiotlb buffer is full (sz: 2097152 bytes)
מאי 16 15:51:38 Arch-Home kernel: radeon 0000:01:00.0: swiotlb buffer is full (sz: 2097152 bytes)
מאי 16 15:51:38 Arch-Home kernel: radeon 0000:01:00.0: swiotlb buffer is full (sz: 2097152 bytes)
מאי 16 15:51:39 Arch-Home kernel: radeon 0000:01:00.0: swiotlb buffer is full (sz: 2097152 bytes)
מאי 16 15:51:39 Arch-Home kernel: radeon 0000:01:00.0: swiotlb buffer is full (sz: 2097152 bytes)
מאי 16 15:51:40 Arch-Home kernel: radeon 0000:01:00.0: swiotlb buffer is full (sz: 2097152 bytes)
מאי 16 15:51:40 Arch-Home kernel: radeon 0000:01:00.0: swiotlb buffer is full (sz: 2097152 bytes)
מאי 16 15:51:41 Arch-Home kernel: radeon 0000:01:00.0: swiotlb buffer is full (sz: 2097152 bytes)
מאי 16 15:51:42 Arch-Home kernel: swiotlb_tbl_map_single: 1 callbacks suppressed
מאי 16 15:51:42 Arch-Home kernel: radeon 0000:01:00.0: swiotlb buffer is full (sz: 2097152 bytes)
מאי 16 15:51:43 Arch-Home kernel: radeon 0000:01:00.0: swiotlb buffer is full (sz: 2097152 bytes)
מאי 16 15:51:43 Arch-Home kernel: radeon 0000:01:00.0: swiotlb buffer is full (sz: 2097152 bytes)
מאי 16 15:51:44 Arch-Home kernel: radeon 0000:01:00.0: swiotlb buffer is full (sz: 2097152 bytes)
מאי 16 15:51:44 Arch-Home kernel: radeon 0000:01:00.0: swiotlb buffer is full (sz: 2097152 bytes)
מאי 16 15:51:45 Arch-Home kernel: radeon 0000:01:00.0: swiotlb buffer is full (sz: 2097152 bytes)
מאי 16 15:51:45 Arch-Home kernel: radeon 0000:01:00.0: swiotlb buffer is full (sz: 2097152 bytes)
מאי 16 15:51:46 Arch-Home kernel: radeon 0000:01:00.0: swiotlb buffer is full (sz: 2097152 bytes)
מאי 16 15:51:46 Arch-Home kernel: radeon 0000:01:00.0: swiotlb buffer is full (sz: 2097152 bytes)
מאי 16 15:51:47 Arch-Home kernel: radeon 0000:01:00.0: swiotlb buffer is full (sz: 2097152 bytes)

this make think those errors seem to be somehow triggering the kernel to swap for some reason
anyone have any idea what could be causing this issue ? and maybe where to report it ?

Last edited by XDarkAngelX (2018-05-20 11:23:59)

XDarkAngelX

Member

Registered: 2014-01-08

Posts: 62

Re: [SOLVED] Kernel swapping too aggressively seems to ignore vm.swappines

After updating to kernel 4.16.9 the errors are gone and so is the aggressive swapping.

Salkay

Member

Registered: 2014-05-22

Posts: 619

Re: [SOLVED] Kernel swapping too aggressively seems to ignore vm.swappines

Hi, did this problem get resolved in the long term for you?

I've been testing various kernels, the current 4.18.16.arch1-1, the current LTS 4.14.78-1, and the previous few LTS versions, and my system is still swapping heavily. I've tried 0 or 1 in /proc/sys/vm/swappiness, and it still swaps. Currently, it's using 1.36G of swap, despite only using 7.90G/31.3G of RAM.