hi mulyadi: 2010/5/20 Mulyadi Santosa <[email protected]>: > On Thu, May 20, 2010 at 14:38, loody <[email protected]> wrote: >> Dear all: >> Where tracing the kernel, 2.6.30, I cannot find "request_irq", which >> is previous devined in kernel/irq/manage.c. > > I think you already saw it, but you didn't really pay attention. It's > include/linux/interrupt.h. Please see > http://lxr.linux.no/linux+v2.6.30.10/include/linux/interrupt.h#L113 > >> I see there is a new function request_threaded_irq seems to replace >> request_irq if I config CONFIG_GENERIC_HARDIRQS. >> But I see other device driver still use request_irq to register their >> interrupt. >> Would anyone tell me where the function lacated and what is the >> difference and why between request_irq and request_threaded_irq? > > I think the best answer is by reading this URL: > http://lwn.net/Articles/302043/ > > Essentially, threaded irq handler is made to reduce latency. To be > precise, by "splitting" top half into 2 parts: one that is just simply > acknowledging the interrupt, and the other to do the real job usually > done inside top half...but this time...the latter is done not by > disabling interrupt (this is my personal understanding, since > logically this is the way to reduce latency) > > -- > regards, thanks for your kind help :) miloody
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