On Saturday, October 27, 2018 1:20:10 PM MDT Jens Axboe wrote:

On Oct 27, 2018, at 12:40 PM, Thomas Fjellstrom [off-list ref] 

wrote:

quoted

Hi

[snip explanation of problem]

Can you try 4.19? A patch went in since 4.18 that fixes a starvation issue
around requeue conditions, which SATA is the one to most often hit.

Gave it a shot. with the vanila kernel from git linux-stable/v4.9. It was a 
bit of a pain as the amdgpu driver seems to be broken for my r9 390 on many 
kernels, including 4.19. Had to reconfigure to the radeon driver, which I must 
say seems to work a lot better than it used to.

At any rate, it doesn't seem to have helped a lot so far. I did end up adding 
"scsi_mod.use_blk_mq=0 dm_mod.use_blk_mq=0" to the default kernel boot command 
line in grub. It seems to have helped a little, but I haven't tested fully 
with a full delete of the build directory. haven't had time to sit and wait 
the 40+ minutes it takes to re build the entire thing. And I'm low enough on 
disk space that I can't easily make a copy of the 109GB build folder. I've got 
about 25GB free out of 780GB. I'll try and test some more soon.

Jens

-- 
Thomas Fjellstrom
thomas@fjellstrom.ca