Date: Mon, 06 Apr 2015 12:01:45 -0700 From: Rui Paulo <rpaulo@me.com> To: freebsd-arch@freebsd.org Subject: Re: x86: finding interrupts that aren't being accounted for? Message-ID: <8818748.ffDquhmdWF@akita> In-Reply-To: <CAJ-Vmok_6SK%2BuwvBsw8bqxOPSHnMbXPiJNBSjHJr3rkqFnPpXg@mail.gmail.com> References: <CAJ-Vmok_6SK%2BuwvBsw8bqxOPSHnMbXPiJNBSjHJr3rkqFnPpXg@mail.gmail.com>
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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? -- Rui Paulo
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