Re: [patch] Real-Time Preemption, -RT-2.6.10-rc1-mm3-V0.7.25-1

From: Shane Shrybman
Date: Fri Nov 12 2004 - 20:04:37 EST

On Fri, 2004-11-12 at 15:13, Ingo Molnar wrote:
> * Shane Shrybman <shrybman@xxxxxx> wrote:
> > V0.7.25-1 has been stable here with the ivtv driver for 11 hrs. No
> > sign of the ide dma time out issue either. Out of curiosity, do we
> > know what solved that problem?
> could you try the attached patch - does it trigger the DMA timeouts
> again? There were 3 changes to the IOAPIC code that could have affected
> your dma-timeout problem, this patch reverts all of them.

Ok, V0.7.25-1 seems to have resolved the DMA timeout problem.

I don't know how useful it is but this patch also seems to have resolved
that problem.

--- linux-2.6.10-rc1mm3-RT3/arch/i386/kernel/io_apic.c 2004-11-11 16:41:37.000000000 -0500
+++ linux-2.6.10-rc1mm3-RT3.T5/arch/i386/kernel/io_apic.c 2004-11-12 17:54:31.000000000 -0500
@@ -156,7 +156,7 @@
* generate lots of spurious interrupts due to the POST-ed write not
* reaching the IOAPIC before the IRQ is ACK-ed in the local APIC.

static void __modify_IO_APIC_irq (unsigned int irq, unsigned long enable, unsigned long disable)
@@ -1940,7 +1940,7 @@
* unacked local APIC is dangerous on SMP as it can prevent the
* delivery of IPIs and can thus cause deadlocks.)
-#if defined(CONFIG_PREEMPT_HARDIRQS) && defined(CONFIG_SMP)

static void mask_and_ack_level_ioapic_irq(unsigned int irq)



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