Bug 682233

Summary: RFE: sysfs: reliably map IRQs to devices
Product: [Fedora] Fedora Reporter: Michal Schmidt <mschmidt>
Component: kernelAssignee: Michal Schmidt <mschmidt>
Status: CLOSED CURRENTRELEASE QA Contact: Fedora Extras Quality Assurance <extras-qa>
Severity: unspecified Docs Contact:
Priority: unspecified    
Version: rawhideCC: gansalmon, itamar, jonathan, kernel-maint, madhu.chinakonda, nhorman, pholasek, sassmann
Target Milestone: ---Keywords: FutureFeature
Target Release: ---   
Hardware: Unspecified   
OS: Unspecified   
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Fixed In Version: Doc Type: Enhancement
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Clone Of: Environment:
Last Closed: 2012-02-02 19:32:41 UTC Type: ---
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description Michal Schmidt 2011-03-04 14:52:05 UTC
My thoughts from a recent discussion about irqbalance:
> IMHO irqbalance should have never relied on the names, because the
> administrator could always rename the devices any way they liked.
> I suspect the problem is that the kernel does not reliably associate
> all the IRQs with devices in /sys. There's /sys/class/net/*/device/irq,
> but it does not tell anything about the MSI-X interrupts the devices
> also use.

(... and AFAIK realtime folks also do similar tricks to set priorities of
the IRQ threads.)

Comment 1 Prarit Bhargava 2011-03-04 16:27:45 UTC
See https://bugzilla.redhat.com/show_bug.cgi?id=502642

also ... I tried to push something like this upstream.  I think that the big issue is that the files associated with the irq must

- be unique
- each contain ONLY one irq value

The problem upstream was then that this results in a large # of files -- and a lot of memory is grabbed because of this ...

P.

Comment 2 Josh Boyer 2012-02-02 17:25:26 UTC
Neil added commit da8d1c8ba4dcb16d60be54b233deca9a7cac98dc to the upstream kernel that is included in 3.3-rc1 (and he backported it to F16).  Does that solve the issue for this bug?

Comment 3 Neil Horman 2012-02-02 18:36:33 UTC
it should, and the latest irqbalance in f16 makes use of that kernel commit to properly identify what kind of device each irq  belongs to.  Given that, I think this is NOTABUG.  Michal?

Comment 4 Michal Schmidt 2012-02-02 19:32:41 UTC
Yes, the commit implements the discussed feature. Closing.