On Tue, Sep 30, 2014 at 11:47:32PM +0200, Oleg Nesterov wrote: > > > This is minor, but this way CONFIG_DEBUG_ATOMIC_SLEEP will not imply > > > a subtle behavioural change. > > > > You mean the __set_current_state() that's extra? > > Yes, and note that it only does __set_current_state(RUNNING) if > CONFIG_DEBUG_ATOMIC_SLEEP. This means that disabling/enabling this > option can, silently hide/uncover a bug. > > > I would actually argue > > to keep that since it makes the 'problem' much worse. > > OK, I won't insist, but could you explain why the suggested change can > make the problem (and which problem ;) worse?
Sure, so the trivial problem is not actually going to sleep in the outer wait primitive because the inner wait primitive reset ->state to TASK_RUNNING. So by always setting the ->state to TASK_RUNNING it never goes to sleep and it'll revert to spinning, causing spikes in CPU usage that should hopefully be far easier to notice than the occasional funny. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
