Hello, I have an application on x86 that uses an external event (either an interrupt or a DMA write to a specific memory location) to trigger code execution, and I believe the local timer interrupt is contributing a significant amount of jitter. This is a bit of a unique case where the only code that should be executing on that core is triggered by the event, so there is no need for anything timer based.
I'm using a dual core processor with a quiet system, and have placed all of the "moveable" interrupts on CPU 0 (0-NR_IRQs using ipipe_set_irq_affinity). Looking at /proc/xenomai/irq and /proc/interrupts shows only the local timer interrupt increment on CPU 1. When using the DMA write to trigger execution, placing "sti"/"cli" around the polling routine improves the jitter substantially. Based on the above, is there some way to do one of the following: 1). Make a user space task higher priority than the timer interrupt or 2). A proper way to disable the local timer (vs. disabling all interrupts) on specific cores, as these cores would only need to run event based routines. Best Regards, Matthew Fornero
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