Date: Mon, 6 Apr 2015 13:37:44 -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-VmonLGg9PE4yEkCinBSFSVU07o9%2BsRHu5syr1cAF8pY_VYA@mail.gmail.com> In-Reply-To: <8818748.ffDquhmdWF@akita> References: <CAJ-Vmok_6SK%2BuwvBsw8bqxOPSHnMbXPiJNBSjHJr3rkqFnPpXg@mail.gmail.com> <8818748.ffDquhmdWF@akita>
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On 6 April 2015 at 12:01, Rui Paulo <rpaulo@me.com> wrote: > On Monday 06 April 2015 00:21:29 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. > > If the cores are being used, you should be getting some samples as to where > the PC is. pmcstat doesn't show that? How about DTrace? Nope, nothing. Nothing at all shows up in the sample based checks. -adrian
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