Bug 215546 - High IRQ 16 CPU usage
Summary: High IRQ 16 CPU usage
Status: RESOLVED DUPLICATE of bug 215533
Alias: None
Product: Drivers
Classification: Unclassified
Component: PCI (show other bugs)
Hardware: Intel Linux
: P1 normal
Assignee: drivers_pci@kernel-bugs.osdl.org
Depends on:
Reported: 2022-01-30 04:24 UTC by David Spencer
Modified: 2022-01-31 19:06 UTC (History)
1 user (show)

See Also:
Kernel Version: 5.16
Tree: Mainline
Regression: No

dmesg output (82.89 KB, text/plain)
2022-01-30 04:24 UTC, David Spencer
lspci output (14.46 KB, text/plain)
2022-01-30 04:25 UTC, David Spencer

Description David Spencer 2022-01-30 04:24:49 UTC
Created attachment 300347 [details]
dmesg output

Dell XPS 9550 (2015)
Arch Linux

On 5.15 and 5.16 kernels, if my laptop is plugged in prior to booting or is plugged in at any time after booting I see high CPU usage (80-100% of a core) by IRQ 16, with a constant 15k+ IRQ events per second, whether the system is in use or not. Unplugging the laptop does not make the events stop. If I boot the system without it being plugged in the issue does not occur until I plug it in. Downgrading to 5.14 fixes the issue completely, with only 3 total IRQ 16 interrupts after the system as been running for > 20 minutes. I do not see IRQ16 interrupts increase by using the touch pad, keyboard, or touch screen. I believe I was able to bisect the introduction of the issue to commit 357cf0cdddceea974a7d32668a0df0d9f77055cb, but this was the first time I've done kernel bisects before, so I may be incorrect. I tested with 5.17 RC1 and the issue was still present.

I've attached dmesg output and the contents of lspci -vvvv, as well as included IRQ 16 info from /proc/interrupts. Please let me know if I can provide anything else.

  16:          0          0    7513443          0          0          0          0          0  IR-IO-APIC   16-fasteoi   idma64.0, i801_smbus, i2c_designware.0
Comment 1 David Spencer 2022-01-30 04:25:37 UTC
Created attachment 300348 [details]
lspci output
Comment 2 David Spencer 2022-01-30 04:32:02 UTC
I think I was incorrect when I said it was in kernel 5.15, when I was bisecting to find the issue the Makefile release information said 5.15-rc2 so I assumed it was in 5.15, but that looks like I was incorrect. I'll test on 5.15 and verify whether it is present there.
Comment 3 David Spencer 2022-01-30 05:41:37 UTC
I've confirmed that I do not see the issue on kernel 5.15, only on 5.16.
Comment 4 joey.corleone 2022-01-31 12:49:00 UTC
Duplicate of https://bugzilla.kernel.org/show_bug.cgi?id=215533.

Thanks for adding your observations on the IRQ events though.
Comment 5 David Spencer 2022-01-31 19:06:05 UTC
Agreed, marked as duplicate.

*** This bug has been marked as a duplicate of bug 215533 ***

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