dealing with interupt storms .....
Michal Mertl
mime at traveller.cz
Fri Nov 12 05:49:13 PST 2004
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
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