# How to deal with an interrupt storm?



## Chris_H (Jul 26, 2018)

OK. Just built a custom kernel. All went as usual. But I appear to be dealing with an interrupt storm. Takes forever to see the keys I press actually echo to the screen. The command `halt -p` takes about 25 minutes to complete after hitting enter. `top -SI` refreshes about once in 20 seconds. It currently shows load averages 8.53, 4.92, 1.78. What?! This a Laptop! `inr` hovers around 33%. But _nothing_ is running -- _nothing_.
I can't really run the usual "status" utilities/commands. Because all I get are "freeze frames" of the output.
Any thoughts on how I might track down the culprit(s)? FWIW this is on a Dell (Pentium M) laptop (i386). src && ports svn(1) up'ped last night (PDT).

Thanks!

--Chris


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## Phishfry (Jul 26, 2018)

What about booting up off a USB Memstick installer and mount the install and edit /boot/loader.conf to load /kernel.old


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## Chris_H (Jul 26, 2018)

Thanks a million for taking the time to reply, Phishfry !
Oh. I don't have any trouble booting it. I can boot single user, and make any adjustments I need/choose. My problem is understanding/finding out *why*. So I can fix it. 

Thanks again, Phishfry !

--Chris


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## Deleted member 45312 (Jul 26, 2018)

What about 
`# vmstat -i`


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## Chris_H (Jul 26, 2018)

dlegrand said:


> What about
> `# vmstat -i`


Since I'm also trying to get FreeBSD to leverage the full capabilities of the Intel (82)915GM* video card in this. I decided to try and spin up a different *BSD. In doing so. I discovered I don't experience the interrupt storm. So evidently, FreeBSD is tickling, or misinterpreting something _other_ BSD', and OS' don't. I'm in the middle of an install on it ATM. But when I'm finished, and have had some time to take a closer look. I should have some useful info, to file a bug report, and patch on bugzilla. Not to mention, a (good) _working_ copy of FreeBSD, on it.

Thanks for taking the time to reply, dlegrand !

--Chris


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## Chris_H (Jul 31, 2018)

OK. `vmstat -i` reveals a very high count for the keyboard. About 1/3rd the total number for the CPU (single core), after an uptime(1) of ~3 minutes.
What would account for this? I'm guessing because of it being trackpad && keyboard?
I have no trouble installing && running 10.4 on it. I may well be able to run 11.(0|1). But 11.2 is for sure the cutoff point. I hit the inability to get (nearly) any output to the console, w/o tapping one of the arrow keys on the keyboard.
I don't know what's blocking. But the interrupts are way too high.

Insights?

Thanks!

--Chris


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## phoenix (Jul 31, 2018)

Since it's a custom kernel, just boot off the original kernel.

Then compare your kernel config file to GENERIC, and make a list of everything that is different.

Then start with GENERIC, make a single change to it, and test it. If everything still works, make one more change, and test it. Repeat until it breaks, and you'll have your culprit.

Will take awhile, sure, but you'll know for sure which change is causing the issue.


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## Chris_H (Jul 31, 2018)

I actually started testing GENERIC installs (accounts for the time span from last post on this to now). Anyway. I can actually see the problem develop during the 11.2 &&11.4 installation. IOW I have to tap an arrow key to get through the "additional user setup". But that just screws up the password (password mismatch). So it takes a couple tries to get through. Then once installed, followed by a reboot. Things just get worse. 

Thanks, phoenix !

--Chris


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## Chris_H (Jul 31, 2018)

OK. Just did a couple more tests. 10.4-SABLE is as far as I can get before getting the intermittent console output. 
I'm browsing the FreeBSD svn repo. But not too hopeful I'll be able to find a clue w/o a *whole* lot of time. 

Any insights *greatly* appreciated! 

--Chris


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## phoenix (Aug 1, 2018)

Which system console driver is used on each system? IIRC, 10.x uses sc(4) by default while 11.x uses vt(4) by default. Maybe the laptop doesn't like how vt works?

You can test that by enabling vt on the 10 install to see what happens, or configure the 11 install to use sc.


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## Chris_H (Aug 1, 2018)

Thanks, phoenix ! I think you're right (about 10x). But because it's got a i915 chipset (video), I enabled vt(4), and loaded the i915kms module. So it's all consistent between versions/systems.

Thank you _very_ much, phoenix , for taking the time to help!

--Chris


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