Date: Tue, 02 Apr 2019 20:58:01 -0600 From: Ian Lepore <ian@freebsd.org> To: Karl Denninger <karl@denninger.net>, ticso@cicely.de Cc: "freebsd-arm@freebsd.org" <freebsd-arm@freebsd.org> Subject: Re: insanely-high interrupt rates Message-ID: <dc56a8964cae942354cbe2b5b0620f2eebb569bb.camel@freebsd.org> In-Reply-To: <d96c7f42-f01b-8990-a558-ee92d631b51d@denninger.net> References: <004ddba628b94b80845d8e509ddcb648d21fd6c9.camel@freebsd.org> <C68D7E6E-03C1-448F-8638-8BD1717DBF44@jeditekunum.com> <ac7d434f16f3a89f5ef247678d6becdbeded5c3f.camel@freebsd.org> <CE40E2B5-2244-4EF9-B67F-34A54D71E2E8@jeditekunum.com> <f60ea6d2-b696-d896-7bcb-ac628f41f7b8@denninger.net> <20190319161423.GH57400@cicely7.cicely.de> <52df098fdc0caf5de1879c93239534fffbd49b56.camel@freebsd.org> <40f57de2-2b25-3981-a416-b9958cc97636@denninger.net> <669892ac3fc37b0843a156c0ab102316829103fd.camel@freebsd.org> <663f2566-b035-7011-70eb-4163b41e6e55@denninger.net> <20190325164827.GL57400@cicely7.cicely.de> <3db9cf8a-68ee-e339-67bf-760ee51464fd@denninger.net> <fc17ac0f77832e840b9fffa9b1074561f1e766d8.camel@freebsd.org> <d96c7f42-f01b-8990-a558-ee92d631b51d@denninger.net>
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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. -- Ian
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