Created attachment 125818 [details]
Amazon propose computer with k520(GK104) GPU for virtualisation (Xen).
You can use Ubuntu LTS on it for example.
When inserting the nouveau driver, /proc/interrupts report that nvkm is doing ~100000 interrupts/sec.
This have been tested on kernel 4.4.0 and 4.4.13.
On amazon, you do not control the real hardware where your system will be run. It appear that sometimes, this issue do not happen. May be this could be due to vbios version ?
Forcing nouveau in headless mode (modeset=2) produce a normal amount of IRQ.
Created attachment 125819 [details]
Created attachment 125821 [details]
dmesg with debug (nouveau.debug=debug drm.debug=0xe)
With another try having modeset=2 does not produce a normal amount of IRQ.
Sorry for the error, it should be due to the randomness of the issue :/
Created attachment 125864 [details]
perf report from perf record -ag
Created attachment 125865 [details]
perf report from perf record -g -C 7
Created attachment 125866 [details]
result from 'cat /proc/interrupts > irq ; sleep 1; cat /proc/interrupts >>irq'
The irq file show that the IRQ on nvkm happens 140954 times in 1 sec.
The perf reports does not show things related to nvkm, but I may not have use the right options for perf
Disabling MSI interrupts (with config="NvMSI=0") reduce the number of IRQ to about 1k/s
Created attachment 129412 [details]
Tracing using ftrace during 1sec
This issue can be reproduce on 4.10-rc10