Date: Fri, 12 Nov 2004 14:49:00 +0100 From: Michal Mertl <mime@traveller.cz> To: "Wilkinson, Alex" <alex.wilkinson@dsto.defence.gov.au>, current@freebsd.org Subject: RE: dealing with interupt storms ..... Message-ID: <4194BF4C.5090007@traveller.cz>
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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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