Date: Wed, 3 Apr 2019 01:51:05 -0700 (PDT) From: "Rodney W. Grimes" <freebsd-rwg@gndrsh.dnsmgr.net> To: Ian Lepore <ian@freebsd.org> Cc: Karl Denninger <karl@denninger.net>, ticso@cicely.de, "freebsd-arm@freebsd.org" <freebsd-arm@freebsd.org> Subject: Re: insanely-high interrupt rates Message-ID: <201904030851.x338p5JG025902@gndrsh.dnsmgr.net> In-Reply-To: <dc56a8964cae942354cbe2b5b0620f2eebb569bb.camel@freebsd.org>
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> On Mon, 2019-03-25 at 12:16 -0500, Karl Denninger wrote: > > On 3/25/2019 12:05, Ian Lepore wrote: > > > On Mon, 2019-03-25 at 11:58 -0500, Karl Denninger wrote: > > > > On 3/25/2019 11:48, Bernd Walter wrote: > > > > > On Mon, Mar 25, 2019 at 11:33:32AM -0500, Karl Denninger wrote: > > > > > > > [insanely high interrupt rates] > > > Is the interrupt rate consistent from second to second? Running > > > 'vmstat 1' for a while might be useful to see that. That many > > > interrupts almost sounds like a line is floating, but if that were > > > the > > > case I'd expect a widely varying number of int/sec. > > > > > > If you build custom kernels, it might be helpful to apply r345475 > > > locally... it will display partial device names instead of just '+' > > > when the name doesn't fit in the vmstat output. > > > > > > -- Ian > > > > No, but it's in the same general range -- around 500k although it does > > flop around some, and occasionally by a lot (e.g. if I sit and watch it > > it'll occasionally put up VERY different numbers -- e.g. a ~730k number, > > then it goes back, etc.) > > > > I don't generally build custom kernels on these but I CAN put this into > > the STABLE tree I'm building that from since I keep a separate one for > > Crochet builds on these boxes. Where do I find that specific delta? (I > > usually just svn things and I don't want to roll it all the way back to > > there, right -- or do I?) > > > > I now have an rpi2b, and I see the same thing you do in the 'vmstat -i' > output, including rates like 500K int/sec on cpu3 timer0. But while it > was behaving like that, the output from 'vmstat 1' showed a perfectly > steady 8800-9200 int/sec, which is certainly more consistent with top > showing under 2% being used for combined system+interrupt. > > I think the problem here is with vmstat -i, not with actual interrupts. > Something about the stats reporting is wrong on armv6/v7. > > Note that this is completely separate from the spurious interrupt > problem, which I still haven't been able to reproduce. I do not know if this data is of any relavance but when I was trying to get a Samsung chrome book snow working: https://wiki.freebsd.org/FreeBSD/arm/Chromebook I had tons of problems with spurious interrupts if I tried to use the internal keyboard. I found that if I plugged a USB keyboard in and never touched the built in keyboard I could infact get booted to multiuser and use the system somewhat. This testing was done on head before the stable/12 branch, I can re-aquire the hardware if there is anyone interested in helping to debug this platform. > -- Ian -- Rod Grimes rgrimes@freebsd.org
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