Date: Mon, 06 Apr 2015 14:15:13 -0700 From: Rui Paulo <rpaulo@me.com> To: Adrian Chadd <adrian@FreeBSD.org> Cc: "freebsd-arch@freebsd.org" <freebsd-arch@freebsd.org> Subject: Re: x86: finding interrupts that aren't being accounted for? Message-ID: <CB014B57-0D75-4ED7-A7EF-871227C3121C@me.com> In-Reply-To: <CAJ-VmonnQKHYaP4aAxbzRGxV3tZF8JVH2FTMp5jehEX2Huvp_g@mail.gmail.com> References: <CAJ-Vmok_6SK%2BuwvBsw8bqxOPSHnMbXPiJNBSjHJr3rkqFnPpXg@mail.gmail.com> <1858440.dQ4AvDcZf7@ralph.baldwin.cx> <CAJ-VmonnQKHYaP4aAxbzRGxV3tZF8JVH2FTMp5jehEX2Huvp_g@mail.gmail.com>
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> 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. -- Rui Paulo
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