Date: Mon, 6 Apr 2015 14:16:23 -0700 From: Adrian Chadd <adrian@freebsd.org> To: Rui Paulo <rpaulo@me.com> Cc: "freebsd-arch@freebsd.org" <freebsd-arch@freebsd.org> Subject: Re: x86: finding interrupts that aren't being accounted for? Message-ID: <CAJ-VmomXn1t6ktfc1wV5bACrwikFK1-Mjb2Q-bJrtLPpAvxpWg@mail.gmail.com> In-Reply-To: <CB014B57-0D75-4ED7-A7EF-871227C3121C@me.com> References: <CAJ-Vmok_6SK%2BuwvBsw8bqxOPSHnMbXPiJNBSjHJr3rkqFnPpXg@mail.gmail.com> <1858440.dQ4AvDcZf7@ralph.baldwin.cx> <CAJ-VmonnQKHYaP4aAxbzRGxV3tZF8JVH2FTMp5jehEX2Huvp_g@mail.gmail.com> <CB014B57-0D75-4ED7-A7EF-871227C3121C@me.com>
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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... Thanks! -a
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