Hi We try to achieve hard real time requirements with a FPGA->IRQ->ISR->User-Space->Kernel-Module->FPGA loop. Kernel IRQ handler which toggles IO pins is executed by a Hardware interrupt every 200us (FPGA). Priority is set to 99 via chrt ?f ?p99 pid-module. Problem: The test is working (Pins are toggled in time, <50us), but for some reason we have randomly (every 2-3sec) big latency times of several ms. We sometimes get already interrupted in our IRQ handler (which we registered with request_irq) before we wakeup our user space task. Kernel Version: linux-socfpga 3.10.37-ltsi-rt37 Development board: Altera Cyclone V SoC Development Kit Do we have to somehow set the priority 99 for the IRQ handler seperately? Is there any kind of priority inheritance from user space task to kernel module? Best Regards Hannes -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
