Re: Real-Time Preemption, -RT-2.6.12-final-V0.7.50-24

From: K.R. Foley
Date: Tue Jul 12 2005 - 11:23:11 EST


Ingo Molnar wrote:
* K.R. Foley <kr@xxxxxxxxxx> wrote:


Ingo Molnar wrote:

* Daniel Walker <dwalker@xxxxxxxxxx> wrote:



I observed a situation on a dual xeon where IOAPIC_POSTFLUSH , if on, would actually cause spurious interrupts. It was odd cause it's suppose to stop them .. If there was a lot of interrupt traffic on one IRQ , it would cause interrupt traffic on another IRQ. This would result in "nobody cared" messages , and the storming IRQ line would get shutdown.

This would only happen in PREEMPT_RT .


does it happen with the latest kernel too? There were a couple of things broken in the IOAPIC code in various earlier versions.

Ingo

Is this why I have been able to boot the latest versions without the noapic option (and without noticeable keyboard repeat problems) or has it just been dumb luck?


yes, i think it's related - the IO-APIC code is now more robust than ever, and that's why any known-broken system would be important to re-check.

Ingo


Well I have booted -27 a couple of times and -28 once now without supplying the noapic boot option and I haven't seen any of the keyboard repeat problems that I reported late last week. This was on my dual 2.6 Xeon w/HT. I have never seen this behavior on any of my older systems. Because of the fact that the problem showed up sporadically, I can't say for sure that it is gone. However, so far so good. I will report any changes that I see.

--
kr
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