From: Tim W. <ti...@sp...> - 2000-12-22 06:48:12
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Interesting... The paper seems to have been quite thoroughly and carefully prepared. However... 1) It applies only to single-CPU systems. 2) It applies to the 8259-PIC - not exactly a high-performance part, and hopefully not relevant to performance-critical drivers on an SMP system. If this sort of thing is the rationale for eschewing interrupt priority levels then that would seem to be flawed in the same way as slavishly implementing them in that they may or may not help depending on the relative performance characteristics of the system. Judging from the paper, it certainly didn't make sense to use them on systems employing the 8259, but that doesn't mean that it doesn't on other (arguably better-designed) systems. x86 systems with an IO-APIC may or may not make the cut :-) Tim On Fri, Dec 22, 2000 at 02:38:23AM +0100, Andi Kleen wrote: > On Thu, Dec 21, 2000 at 05:13:08PM -0800, Tim Wright wrote: > > On Thu, Dec 21, 2000 at 11:51:39PM +0100, Andi Kleen wrote: > > > I doubt that there would be many chances to get generally visible spl levels into > > > Linux -- Torvalds et.al. have a near religious aversion against them. > > > > > > > Yes, I sort of gathered that. I've not seen any explanation of this antipathy. > > One argument is e.g. > http://www.usenix.org/publications/library/proceedings/ana97/full_papers/small/small.html > > > -Andi -- Tim Wright - ti...@sp... or ti...@ar... or tw...@us... IBM Linux Technology Center, Beaverton, Oregon "Nobody ever said I was charming, they said "Rimmer, you're a git!"" RD VI |