fyi: 11.0-current rpi2 systat -vmstat shows around 24k interrupts for bcm283x_dw

[Hans Petter Selasky]

On 12/26/15 21:51, Mark Millard wrote:
> Context:
>
>> # freebsd-version -ku; uname -aKU
>> 11.0-CURRENT
>> 11.0-CURRENT
>> FreeBSD rpi2 11.0-CURRENT FreeBSD 11.0-CURRENT #2 r292413M: Fri Dec 25 18:03:19 PST 2015     root at FreeBSDx64:/usr/obj/clang/arm.armv6/usr/src/sys/RPI2-NODBG  arm 1100091 1100091
>
>
> For a basically near-idle context systat -vmstat lists "Int" and 23k to 25k normally (almost always 24k) and bcm283x_dw at the right shows figures like 24118. "generic_ti" is more like 232 and "ipi 76" is more like 111. The others at the right are normally blank (other than total).
>
> Lots of bcm283x_dw interrupts if around 24k is correct. As the numbers do not change scale when the systat refresh interval is explicitly scaled, I assume that the figures are per second (or per some other time unit, possibly just for the most recent unit instead of mean).
>
> I'm not sure it will be readable but the below is a capture of a systat -vmstat display.
>

Hi,

The dwc_otg needs to be served frequently in PIO mode. Your number is 
expected. We're using fast interrupts for most of this work, so no 
task-switching is involved and so the CPU consumption remains low.

You can disable USB like this:

usbconfig -d 0.1 set_config 255

And the interrupts should go down to zero.

Re-enable like this:

usbconfig -d 0.1 set_config 0

--HPS