Date: Mon, 6 Apr 2015 13:38:28 -0700 From: Adrian Chadd <adrian@freebsd.org> To: John Baldwin <jhb@freebsd.org> Cc: "freebsd-arch@freebsd.org" <freebsd-arch@freebsd.org> Subject: Re: x86: finding interrupts that aren't being accounted for? Message-ID: <CAJ-VmonnQKHYaP4aAxbzRGxV3tZF8JVH2FTMp5jehEX2Huvp_g@mail.gmail.com> In-Reply-To: <1858440.dQ4AvDcZf7@ralph.baldwin.cx> References: <CAJ-Vmok_6SK%2BuwvBsw8bqxOPSHnMbXPiJNBSjHJr3rkqFnPpXg@mail.gmail.com> <1858440.dQ4AvDcZf7@ralph.baldwin.cx>
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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? -adrian
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