On Wed, 26 Jan 2005, Benjamin Herrenschmidt wrote: > On Tue, 2005-01-25 at 16:34 -0800, Christoph Lameter wrote: > > > I just hope that the implementation of one arch does not become a standard > > without sufficient reflection. Could we first get an explanation of > > the rationale of the offsets? From my viewpoint of the ia64 implementation > > I have some difficulty understanding why such complicated things as > > prescale and postscale are necessary in gettimeday and why the simple > > formula that we use in gettimeofday is not sufficient? > > What is complicated here ? The formula, at least as we do on ppc64, is > simply: > > time = (hw_value - prescale offset) / scale + post scale offset
Yes that is basically what we do on ia64 but we use different terminology. time = ns_at_last_tick + (hw_value - last_tick_hw_value) * scale >> shift > > What I think is a priority need is some subsystem that manages > > time sources effectively (including the ability of the ntp code to > > scale the appropriately) and does that in an arch independent > > way so that all the code can be consolidated. Extract the best existing > > solutions and work from there. > > Which is what John is trying to do, so help instead of criticizing :) I sure hope that we will be doing that. But so far this has been a new implementation instead otherwise ntp_scale would not be in the gettimeofday function. - 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/
