Antonio Del Cinque wrote: [...] >Then I open an ssh connection with the target, and run a "cat /dev/zero > file". The target >is mounted on an NFS root filesystem, so this generates a high number of >fast ethernet interrupts. Now the oscilloscope shows 15 uS jitter in the worst case, >and a visible variance. I would assume this effect as increased max latency.
This figure has already been seen with SoC in the range of the e300, and sometime worse. >The ethernet interrupt is handled only in Linux domain by the original vanilla handler, >but Linux should be stalled/preempted when the timer interrupt occurs. So I assume >that latency is to be justified by the time it takes to adeos to record an >ethernet interrupt event in the i-logs when the timer interrupt is executing or ready to >execute. Is this correct? Cache miss and TLB miss are also good latency killers. To some extent, long DMA transfers can bog down the system bus. >Is there any way to lower max latency for the timer interrupt? Has anybody tried to play with cache locking? -- Stephane _______________________________________________ Xenomai-help mailing list [email protected] https://mail.gna.org/listinfo/xenomai-help
