> pseudo-interrupt from user space There's nothing pseudo about it. Again, any usual way to have a userspace application respond to an interrupt will be the exact same. The kernel will block the userspace process until the interrupt is seen. The only real alternative is burning up the cpu with memory polling, which appears to be what the BBIOlib method uses. So, your latency is limited to your poll speed (which can be faster than interrupts). But, if you have a constant poll for minimum latency, lets hope you're not trying to do something important elsewhere since your cpu usage will be at 100%, and you'll be maximizing process to process context switching!
For 4, The only difference between a userspace and kernel space interrupt handler is where the code is that responds to the interrupt. You will only benefit from writing your own interrupt handler if you put all of your code that does something with that interrupt in the kernel. Otherwise, you're back to process blocked by kernel, interrupt occurs, kernel unblocks process, process does something after seeing the interrupt....back to the sysfs/UIO method. I would try some benchmarks. See if the regular UIO/sysfs interrupt method gives you sufficient performance. And definitely keep in mind John's statement. You're going to see a massive amount of jitter for anything in userspace or kernel space (better jitter since you can disable interrupts and whatnot, but if you don't finish quickly in kernel space, you'll crash the kernel). If something like a precise timestamp is needed for an async event, then there are other ways to approach this. If you're looking for fixed low latency, you're doomed. On Wed, Sep 10, 2014 at 5:13 AM, neo <prag.in...@gmail.com> wrote: > pseudo-interrupt from user space -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to beagleboard+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
