On Fri, 4 Jun 2010, Ingo Molnar wrote: > Note that this does not necessarily have to be implemented as 'execute suspend > from the idle task' code: scheduling from the idle task, while can certainly > be made to work, is a somewhat recursive concept that we might want to avoid > for robustness reasons. > > Instead, the 'deepest idle' (suspend) method could consist of a wakeup of a > kernel thread (or of any of the existing kernel threads such as the migration > thread) - which kernel thread then does a race-free suspend: it offlines all > but one CPU [on platforms that need that] and then initiates the suspend - but > aborts the attempt if there's any sign of wakeup activity. Out of morbid curiosity... A typical sign of wakeup activity is a thread becoming runnable because of expiration of a kernel timer or an I/O completion interrupt. How would the "race-free suspend" thread detect this sort of thing? Indeed, isn't the inability to detect these part of what makes the existing suspend implementation (the freezer in particular) not race-free? Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
