RT-Preemption is causing Very-High Interrupt Latency

From: p_ashish
Date: Mon Aug 18 2008 - 02:03:24 EST



I applied RT-preemption and High-Resolution Timer Patch to linux-2.6.19.2 .
It gave satisfactory result for 'cyclic_test' and
'HR-Timer clock-nanoSleep_test'.

But the problem is that Interrupt Latency in much more than before.
This is result which i got from my Interrupt Latency program.

WITH RT-preemption:
(Max Latency= 513.1 micro seconds and Min Latency= 12.1 micro seconds)

WITHOUT RT-preemption:
(Max Latency= 13.1 micro seconds and Min Latency= 1.8 micro seconds)


Since, RT-preemption implements ISR like threads, so is this the reason for
higher latency? Is there any way to improve this?

regards
~ashish






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