Re: ARM Linux Suitability for Real-time Application

[Andrew Lewis <andrew-lewis@netspace.net.au>]

Russell King wrote:
> On Wed, Jun 22, 2005 at 09:52:40AM -0700, Daniel Walker wrote:
> 
>>On Wed, 22 Jun 2005, Russell King wrote:
>>
>>>If you're just after some background process to run off interrupts with
>>>minimal interrupt latency, the good news is that you don't have to modify
>>>the kernel on ARM, and you certainly don't need any RT patches.
>>>
>>>If you use the FIQ, then your FIQ latency will be the time it takes the
>>>CPU to enter your FIQ function.  Since the kernel _never_ disables FIQs
>>>in any way, FIQs have ultimate priority over everything else in the
>>>system.
>>>
>>
>>Aren't FIQ's only on some ARM's ? 
> 
> 
> Yes, but please read the original mail.  I think you'll find my reply
> is completely relevant to the question being posed, which was based
> upon the AT91RM9200 SoC.

Thanks for the suggestions.  The FIQ solutions sounds like the one to 
use.  I'll probably do a little testing sometime in the next few weeks 
to determine the maximum loading I can place on the processor when 
running some of the other peripherals simultaneously.  If I have time 
I'll test the -RT patches as well and post up some numbers for this 
processor.