RE: dealing with interupt storms .....

Alext Wilkinson wrote:

> Hi all,
> 
> How does one stop an interrupt storm in RELENG_5 ?
> 
>> >From top(1)
> 
> CPU states: 10.9% user,  0.0% nice,  3.9% system, 85.3% interrupt,  0.0% idle
> 
> >From vmstat(1)
> 
>                                  total          rate
>                                  -----          ----
> irq18: uhci2 bt0++               9187313        426

Answer to your question might be to modify sysctl hw.intr_storm_threshold.

I can confirm, there is a problem in bktr(4) generating interrupt storms. For several months I was seeing messages about interrupt storms and system run fine (I haven't been using bktr for long time so I didn't care). I tried to roll the bktr sources as far back as possible (that is to the time before phk changed dev_t to struct cdev *) to no avail, so I suspect the problem is caused by something outside of the driver. After latest changes to interrupt throttling (rev. 1.117 of src/sys/kern_intr.c by jhb) the system performance is pretty affected until I unload bktr driver because bktr now seems to be doing some 120000 interrupts/second and not getting throttled).

--
Michal Mertl