On 11/04/2009 11:44 PM, Clark Williams wrote: > On Wed, 04 Nov 2009 18:32:41 +0100 > Tim Blechmann <tim@xxxxxxxxxx> wrote: > >>>> 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 ... >> > > No, we need to get that fixed in the wiki. It may have been the case > that the entire process was frozen while a fault was being handled, but > I don't believe that is the case now. If you're in a thread on core0 > and a sibling thread on core1 faults, you shouldn't be impacted unless > you're trying to reference the same memory. well, then my application seems to be real-time safe ... it would be nice if the wiki would reflect the current state of the rt-preempt kernel, though ... thnx, tim -- tim@xxxxxxxxxx http://tim.klingt.org All we composers really have to work with is time and sound - and sometimes I'm not even sure about sound. Morton Feldman
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