Re: rt file i/o

[Tim Blechmann <tim@klingt.org>]

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>> well, if i understand the rt howto correctly, _no_ disc access is
>> allowed, neither from rt nor from non-rt threads, since it may produce
>> page faults, which introduce latencies ...
> 
> I would be supprised if the rt howto states that page-faults in non-rt
> threads is a critical problem - that would not significantly impact RT
> performance - atelast not the worst case - it will (as every other system
> load) impact the average case. so having a non-rt thread reading disk-files
> to a buffer and a rt-thread processing this buffer should be perfectly fine.

that is what i thought for years ... but according to [1] a page fault
in an rt process freezes the entire process with both rt and non-rt
threads until the page fault is handled ...

tim

[1]
http://rt.wiki.kernel.org/index.php/HOWTO:_Build_an_RT-application#Latencies_caused_by_Page-faults

-- 
tim@klingt.org
http://tim.klingt.org

Your mind will answer most questions if you learn to relax and wait
for the answer.
  William S. Burroughs


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