Hi! On Thursday 08 November 2007, you wrote: > Hi! > > I'm thinking about adding the priority ceiling protocol to -rt > (implemented in a way so that you can select between priority > inheritance and priority ceiling with the kernel configurator). > > Since this mechanism inherently avoids dead-locks, it could be > helpful for applications that need high safety integrity levels!? > > The priority ceiling protocol is basically no rocket science > and implemented for other OSes for a while, so it should be > a no-brainer get it going with Linux. However. I'm struggling > at the point where it comes to SMP: it seems like when a task > acquires a lock, it is necessary to un-schedule any active > tasks on other cores sharing the same lock. This would be > very inefficient, of course, because tasks sharing a lock > couldn't run in parallel on different CPUs. > > Does anybody know of any other priority inversion and > dead-lock avoidance mechanism that would efficiently work > on SMP? > > Feedback is highly appreciated! > > regards > > Bernhard Maybe I didn't completely understood your question, but... if there is a problem with SMP efficiency (I do not really know, but believe you :) ) with priority ceiling (PC) implementation, this problem should have been already identified (and possibly solved) in the current PI implementation, right? As far as I know (and I might be wrong), the PC is very similar to the PI. Main difference is that for the PC, the priority burst is to the lock ceiling value instead of the higher priority task that accesses the lock. (BTW, what do you think that should be the kernel behaviour when the ceiling value is violated? Typical solution in RTOS is to have a fatal error) Best regards -- Luís Henriques - 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
