linux-kernel - Re: POWER9: duplicate interrupt line in /proc/interrupts, kernel problem or userspace problem?

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Message-ID: <877bzxdg9m.fsf@mpe.ellerman.id.au>
Date: Thu, 24 Jul 2025 20:39:33 +1000
From: Michael Ellerman <mpe@...nel.org>
To: Simon Richter <Simon.Richter@...yros.de>, linuxppc-dev@...ts.ozlabs.org,
 linux-kernel@...r.kernel.org
Subject: Re: POWER9: duplicate interrupt line in /proc/interrupts, kernel
 problem or userspace problem?

Simon Richter <Simon.Richter@...yros.de> writes:
> Hi,
>
> I have two lines starting with "LOC:" in /proc/interrupts, one with a 
> comment "Local timer interrupts for timer event device", the other 
> "Local timer interrupts for others".
>
> This makes collectd unhappy, because it uses the first column as a 
> unique identifier.
>
> Is this column supposed to be unique? (i.e. is this a kernel bug, or 
> should collectd expect this?)

It probably is supposed to be unique. In the early days it was just the
irq number (which is unique), and then later the named entries were
added. There's no formal spec for the format, and it's really intended
to be human readable, so who can say for sure.

But yeah I think it's reasonable to call it a powerpc kernel bug.

Having said that, it's been like that on powerpc since 2013, so although
we can fix it now, there's 12 years of kernels out there that have the
duplicate entries.

cheers