Date: Mon, 6 Apr 2015 00:21:29 -0700 From: Adrian Chadd <adrian@freebsd.org> To: "freebsd-arch@freebsd.org" <freebsd-arch@freebsd.org> Subject: x86: finding interrupts that aren't being accounted for? Message-ID: <CAJ-Vmok_6SK%2BuwvBsw8bqxOPSHnMbXPiJNBSjHJr3rkqFnPpXg@mail.gmail.com>
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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! -adrian
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