On Tue, 23 Jun 2015 11:20:38 -0500 Gary Robertson <gary.robertson@xxxxxxxxxx> wrote: > I am concerned about interactions with the evolving 'full tickless' operations. I'm concerned about more than just full tickless. But like you, I don't currently have any concrete examples to show there's a possible issue. > > While I have no concrete use cases to show, I can conceive that > an I/O data processing application running on an isolated core > operating in 'full tickless' mode might benefit from allowing interrupts > on that same core so long as they service hardware involved with > the data flow being processed by the application. > Let's further assume that for hardware-related reasons we still want > to run the irq work from a softirq context rather than a hardirq context. > > In such circumstances we obviously don't want the irq work done from a > timer tick - > so adding another irq work queue independent of the lazy flag and > unconditionally raising a softirq on the first addition to that queue > would seem to be the most flexible and compatible answer. > Irq work queued with the lazy bit set could be deferred until the next > tick interrupt > for efficiency and compatibility, and 'normal' irq work > would no longer be potentially stalled > by being enqueued with 'lazy' work. I'd be sleeping better at night with a third queue. I'll write up a patch and post that as an RFC as well. This will at a minimum keep with the paradigm of mainline linux. -- 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
