On Fri, Oct 7, 2016 at 3:32 AM, Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> wrote: > On 2016-10-06 20:15:16 [-0700], Joel Fernandes wrote: >> Hi Sebastian, > Hi Joel, > >> > > So basically my questions are: >> > > 1. Does hard in hard irq mean hardware interrupt or does it imply >> > > interrupt context? >> > >> > I would drop that hard part. It is an interrupt handler. It then can be >> > either threaded or not and it can be always threaded or sometimes. >> > hard is used to distinguish this kind of interrupts from the soft-irqs. >> > >> >> But with threaded interrupts, you do have a handler that wakes up the >> thread. In this case there are 2 handlers, one handler executes in >> interrupt context and wakes up the thread, and the other runs in the >> thread. In this case, the term "interrupt handler" is confusing since >> it isn't clear which handler we're referring to. "hard interrupt >> handler" is also confusing - since if hard means "hardware", then >> technically the thread is also a "hard interrupt handler" since the >> interrupt line is masked (forced threaded interrupts are also one >> shot) till the thread clears the interrupt reason. > > so what is your point? You still have a primary handler and a secondary > / threaded handler. My point is its hard (no pun intended) to find a set of terms to describe a handler to clearly define its context (interrupt vs process context). I see "hard IRQ handler" mentioned in different documentation referring to interrupt context but as we discussed this isn't the case. Thanks for referring to primary and secondary, I will use these to differentiate between the 2 handlers. :) > In -RT (!RT, too but I am not 100% sure) we can have three. Now I leave > it to your research to figure out when this might happen :) > I guess primary and secondary also don't accurately describe context anymore because of force threading of primary handlers [1] (which I think is what you meant about having 3 handlers? :)) so I will just be explicit about the context if I need to mention it in conversation. So like "threaded primary handler". Thanks, Joel [1] https://lkml.org/lkml/2015/9/21/124 -- 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
