On Fri, 31 Jan 2014 20:26:54 +0100 Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> wrote: > On 01/31/2014 06:57 PM, Steven Rostedt wrote: > > > In vanilla Linux, irq_work_run() is called from update_process_times() > > when it is called from the timer interrupt. In -rt, there's reasons we > > and in vanilla Linux some architectures (like x86 or sparc to name just > a few) overwrite arch_irq_work_raise() which means they provide > their "own" interrupt like callback. That means on those architectures > irq_work_run() gets invoked twice: once via update_process_times() and > via and once the custom interface. > So my question to the original inventor of this code: Peter, do we > really need that arch specific callback? Wouldn't one be enough? Is it > that critical that it can't wait to the next timer tick? There's flags that determine when the next call should be invoked. The irq_work_run() should return immediately if it was already done by the arch specific call. The work wont be called twice. As I have worked on code that uses irq_work() I can say that we want the arch specific interrupts. For those architectures that don't have it will experience larger latencies for the work required. It's basically, a "too bad" for them. But to answer your question, no we want the immediate response. -- Steve -- 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
