On Fri, 14 Jun 2013, Ming Lei wrote: > On Fri, Jun 14, 2013 at 3:41 AM, Alan Stern <[email protected]> wrote: > > > > The main reason for moving away from the current scheme is to reduce > > latency for other interrupt handlers. Ming gave two examples of slow > > USB code that runs in hardirq context now; with his change they would > > run in softirq context and therefore wouldn't delay other interrupts so > > much. (Interrupt latency is hard to measure, however.) > > With the two trace points of irq_handler_entry and irq_handler_exit, the > interrupt latency(or the time taken by hard irq handler) isn't hard to > measure. > One simple script can figure out the average/maximum latency for one irq > handler, like I did in 4/4.
But that doesn't measure the time between when the IRQ request is issued and when irq_handler_entry runs. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
