Hi, On Tue, 7 Aug 2007, Andrew Morton wrote:
> > The current msleep is fine and doesn't need any "fixing". > > Not all the world is i386, _please_ keep hrtimer usage where it's > > required. Simple timer should be given preference unless the higher > > resolution is really needed, which is not the case here. > > Hang on. Having msleep(1) sleep for 20 milliseconds is really awful > behaviour. Possibly worse is the fact that with other configs, it will > delay for eight milliseconds. Or two. That's an order of magnitude of > unpredictability which can actually cause driver breakage. > > Fixing that *bug* is a good thing. I see no reason why we should "keep > hrtimer usage where it is required"? The implementation details are hidden > from the caller. This is not a bug. You have to keep in mind that for hrtimer to make a real difference HIGH_RES_TIMERS has to be enabled, OTOH if HZ is already set to 1000, it doesn't make much difference. The sleep was and will be only a minimum time, expecting something different is actually a bug. > > so below is a nanosleep implementation based > > on Jonathan's patch. This will user give a choice, so there is no need to > > force all users to use hrtimer for a simple sleep. > > But apart from needlessly fattening the kernel API, that leaves us in the > current situation where an unknown number of the msleep() callers actually > care that they are calling a function which by a huge margin fails to do > what they are asking it to do. It will take a long time to hunt down all > the problematic callsites and migrate them to nanosleep(). As I tried to say before this is foremost an API issue. Introducing nanosleep() makes it clear that this user will benefit from enabling HIGH_RES_TIMERS, whereas msleep() says that resolution is not that important and thus it will work fine without HIGH_RES_TIMERS and/or HZ_1000. bye, Roman - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
