Messages in this thread | | | Date | Wed, 20 Jun 2012 10:23:39 -0700 | From | "H. Peter Anvin" <> | Subject | Re: [tip:x86/apic] x86/apic: Try to spread IRQ vectors to different priority levels |
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On 06/08/2012 07:50 AM, tip-bot for Alexander Gordeev wrote: > Commit-ID: 1bccd58bfffc5a677051937b332b71f0686187c1 > Gitweb: http://git.kernel.org/tip/1bccd58bfffc5a677051937b332b71f0686187c1 > Author: Alexander Gordeev <agordeev@redhat.com> > AuthorDate: Thu, 7 Jun 2012 15:15:15 +0200 > Committer: Ingo Molnar <mingo@kernel.org> > CommitDate: Fri, 8 Jun 2012 11:44:28 +0200 > > x86/apic: Try to spread IRQ vectors to different priority levels > > When assigning a new vector it is primarially done by adding 8 > to the previously given out vector number. Hence, two > consequently allocated vector numbers would likely fall into the > same priority level. Try to spread vector numbers to different > priority levels better by changing the step from 8 to 16. >
OK, stupid question: WHY?
In general, in Linux the random prioritization is actually a negative. The only reason for the spreading by 8 is because of bugs/misfeatures in old APIC implementations which made them handle more than two interrupts per priority level rather inefficiently.
-hpa
-- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf.
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