Date: Mon, 06 Apr 2015 17:28:02 -0400 From: John Baldwin <jhb@freebsd.org> To: Adrian Chadd <adrian@freebsd.org> Cc: "freebsd-arch@freebsd.org" <freebsd-arch@freebsd.org>, Rui Paulo <rpaulo@me.com> Subject: Re: x86: finding interrupts that aren't being accounted for? Message-ID: <71486315.GsjOnd645i@ralph.baldwin.cx> In-Reply-To: <CAJ-VmomXn1t6ktfc1wV5bACrwikFK1-Mjb2Q-bJrtLPpAvxpWg@mail.gmail.com> References: <CAJ-Vmok_6SK%2BuwvBsw8bqxOPSHnMbXPiJNBSjHJr3rkqFnPpXg@mail.gmail.com> <CB014B57-0D75-4ED7-A7EF-871227C3121C@me.com> <CAJ-VmomXn1t6ktfc1wV5bACrwikFK1-Mjb2Q-bJrtLPpAvxpWg@mail.gmail.com>
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On Monday, April 06, 2015 02:16:23 PM Adrian Chadd wrote: > On 6 April 2015 at 14:15, Rui Paulo <rpaulo@me.com> wrote: > > > >> On Apr 6, 2015, at 13:38, Adrian Chadd <adrian@FreeBSD.org> wrote: > >> > >> On 6 April 2015 at 12:18, John Baldwin <jhb@freebsd.org> wrote: > >>> On Monday, April 06, 2015 12:21:29 AM Adrian Chadd wrote: > >>>> Hi, > >>>> > >>>> I have an .. odd problem on a Lenovo X230. > >>>> > >>>> I just threw in a very old wifi card (Intel 3945) into the expresscard > >>>> (pcie) slot. Now, we don't have any pcie-hp support in -HEAD just yet, > >>>> but i wasn't expecting the system to crawl to a halt. > >>>> > >>>> When I unplug it, everything returns to normal. > >>>> > >>>> Other cards don't do this. > >>>> > >>>> So, I figured it may be interrupt spam - but vmstat -ia shows no > >>>> interrupts going crazy. > >>>> > >>>> pmcstat -S CPU_CLK_UNHALTED_CORE -T -w 5 doesn't register anything > >>>> either - only a handful of background samples. > >>>> > >>>> However, /counter/ mode pmc tells a different story - pmcstat -s > >>>> CPU_CLK_UNHALTED_CORE -w 1 shows all four cores going at 110% when the > >>>> card is inserted, with brief periods of idle. Once I remove the card, > >>>> the counters go back down to zero. > >>>> > >>>> My working theory is: something is chewing CPU and it's likely > >>>> interrupts, but if it is, it's something far, far earlier than the x86 > >>>> interrupt C code, which counts interrupts and spurious events. > >>>> > >>>> So - has anyone diagnosed this stuff on FreeBSD/x86 before? I was kind > >>>> of hoping we'd at least get accurate statistics about spurious > >>>> interrupts, and if we don't, I'd like to understand why. > >>>> > >>>> Thanks! > >>> > >>> SMM? Perhaps SMM doesn't hide itself from PMC counters (but it can hide itself > >>> from samples). > >>> > >>> If it is SMM there's not really anything you can do about it. Try getting a > >>> KTR_SCHED trace and looking at it in schedgraph. When I've seen SMM isuses in > >>> the past it shows up as hole in the graph where nothing happens in the system. > >>> > >>> In your case you could perhaps be getting PCI errors that are triggering the > >>> SMM handler. Perhaps compare pciconf -le before and after to see if there are > >>> any changes. > >> > >> Hm, ok. Can we extract PCIe errors yet? > > > > Yes, check pciconf. > > I'll try, but the system is pretty unusable whilst the card is plugged in... PCI errors latch. You can run 'pciconf -le' after you yank the card back out. I would just do this: 'pciconf -le > before' <insert card and yank it back out> 'pciconf -le > after' Compare before and after using something like 'kompare'. -- John Baldwin
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