Re: [gentoo-user] More emerge oddity in chroot - SOLVED

[Peter Humphrey <peter@prh.myzen.co.uk>]

On Monday 28 Apr 2014 13:32:05 I wrote:
> On Thursday 24 Apr 2014 13:57:19 I wrote:
> > So far I've done these things:
> > 
> > 1. Wiped the whole system and restored from backup (heavy overkill, but I
> > wanted everything to be in the same, consistent state).
> > 2. Run bad-blocks tests on all partitions (though all but / and /boot  are
> > in logical volumes - I don't know to what extent that will have affected
> > the results).
> 
> --->8
> 
> Looking at bad-blocks again, I see from gkrellm that 'mkfs.ext4 -cc -L Atom
> /dev/vg7/atom' writes the test patterns to both the underlying physical
> disks, but it only reads back from one of them

... so it isn't much use on a virtual disk.

Well, that was a long weekend.

The symptoms grew stranger and stranger, until I eventually discovered a
problem with IRQ 16.

/proc/interrupts includes this line:
 16:      0   302525      0      0   IO-APIC-fasteoi  ehci_hcd:usb1, nouveau

The source file /usr/src/linux/kernel/irq/spurious.c says:

/*
 * If 99,900 of the previous 100,000 interrupts have not been handled
 * then assume that the IRQ is stuck in some manner. Drop a diagnostic
 * and try to turn the IRQ off.
 *
 * (The other 100-of-100,000 interrupts may have been a correctly
 *  functioning device sharing an IRQ with the failing one)
 */

...and suggests booting with irqpoll.

So I added irqpoll to the kernel command line. It seemed to make no difference
at the time, but I haven't had any recurrence in the last two days. I see 
though that, according to gkrellm, I have core temps of 52 - 56C and the 
graphics card shows 59C. That shouldn't be hot enough to start raising 
spurious interrupts: the nVidia web site says to expect around 105C as a 
limit. Perhaps I should find a different slot for the Quadro FX580 card, to 
separate it from the usb interface.

So, many hours and much rebuilding later, I've installed a new chroot for the 
Atom and it seems to be working as expected. Actually, I reinstalled the 
entire system to be safe, including re-creating the physical and logical 
volumes on the two SATA disks.

The question still remaining is what caused millions of spurious interrupts 
over a period of a week or so and then subsided. This is an Asus P7P55D 
motherboard (http://www.asus.com/Motherboards/P7P55D/).

-- 
Regards
Peter