AFAIK mmc driver currently does not support BFQ.Ollittm wrote: ↑Fri Sep 15, 2017 6:24 pmI have kernel 4.12 working just fine compiled from source. However if I try to enable BFQ support, RPi fails to boot. In fact it does not seem to be able to grok the sdcard at all.
In the cmdline.txt I simply changed elevator=deadline to elevator=bfq and compiled the kernel with the BFQ options. There's also some other discussion about scsi option in cmdline and making UDEV rule but neither of these helped.
So, 4.12.11 kernel for RPi just doesn't work with BFQ?
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cat /sys/block/mmcblk0/queue/scheduler [noop] deadline cfq
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cat /sys/block/sda/queue/scheduler [mq-deadline] kyber bfq none
If you look at google results on getting BFQ to work, this is normal and it should be replaced by the MQ options including BFQ when you have the configuration options set up correctly. Which is what I spent some time struggling with.
Agreed, at least kernel could get it's own subforum, having it buried in "Operating system distributions" - "other" seems wrong to me.
I'm using 4.13 from the Raspberry Pi github, everything seems to work on that. Not seen a single problem. Is there a reason you cannot use that?Ollittm wrote: ↑Tue Sep 19, 2017 12:09 pmI decided to go back to 4.9.y kernel. Given that the 4.10 and above lag thousands of commits behind 4.9.y, they're not working quite properly. Wifi does not work and neither does bluetooth. Desktop is misbehaving.. I'm sure there are ways to get around it, probably you can just tell git somehow to patch the missing commits in.
I decided to grab 4.9.y and patch the writeback throttling and BFQ in. It appears the "legacy" patches for <4.12 kernels do indeed support single queue operation as well. Theoretically having both enabled is redundant as they try to achieve the same thing in different ways.
On the writeback discussion it would seem that the problem cannot be fixed by IO scheduler as it's the disk buffer that gets overrun when you copy lots of stuff to a slow medium from a faster one. Or do something like install kernel headers..
As I commented in the other thread, the problems were caused by "/lib/firmware" directory getting wiped out at some part from the RPi. Kernel installation does not recreate everything in that dir, is it supposed to?
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