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SubjectRe: interrupt latency k2.4 / i386?
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On Fri, Feb 07, 2003 at 06:47:36PM +0000, SA wrote:
>
> Dear list,
>
> What latency should I expect for hardware interrupts under k2.4 / i386 ?
>
>
>
> ie how long should it take between the hardware signalling the interrupt and
> the interrupt handler being called?

I don't know the hardware part but it depends on how long interrupts are
being disabled (and that depend on the code you use in the kernel) and
that can be measured with akpm's timepeg+intlat patches

http://www.zip.com.au/~akpm/linux/#timepegs

I hope this helps

Ulisses

>
>
> I am wrting a driver which pace IO with interrupts, generating one interrupt
> for after every transfer is done. Looking at the hardware schematics the
> interrupts should occur virtually instantly after each transfer but the
> driver is waiting ~1ms/ interrupt.
>
> I can use polling instead with busy waits but this seems a bit wasteful.
>
>
> My interrupt is shared with my graphics card using the non-GPL nvidia driver -
> could this be responsible for the delay (any experience with this)?
>
> cat /proc/interrupts
> .....
> 10: 3028 XT-PIC eth0, VIA 82C686A
> 11: 1117037 XT-PIC nvidia, PI stage <-- my driver
> 12: 14776 XT-PIC usb-uhci, usb-uhci
> .....
>
> Thanks SA
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