I am curious about interrupt latency. I have an Embedded Planet RPX Classic CLLF_BW31 MPC860 running at 48Mhz with non-realtime Hard Hat 1.2 with the 2.2.14 kernel.
In general what kind of interrupt latency can I expect? I am seeing a pretty consistent 10 us min IRQ2 latency but occassionally see up to 70 us max. I am not using IRQ0 or IRQ1 (therefore IRQ2 is highest priority) and we monitored this with my application code doing next to nothing. Basically I am only running ISR2. First, I was surprised the 10 us min latency, I thought I might occassionally see a much quicker response. Second, I was surprised to see the occassional slow response of 70 us max. It would be nice if we could get the max under 50 us. Or do you have to go to a real-time kernel? I am looking into my code to see that I am not masking the interrupt for too long (or even at all) and checking the driver code efficiency. Could the non-realtime linux kernel mask the interrupts for that long? I am going to look into what all linux is doing, I am thinking it is not doing much but have not verified this. I tried to find some general interrupt latency numbers on the web through Monta Vista or others but did not find anything relevant. Jon Baker =================================== Jon Baker Software Engineer Efficient Channel Coding, Inc. 216-635-1610 www.eccincorp.com =================================== ** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/
