On Tue, 2005-01-25 at 15:09 -0800, john stultz wrote: > The performance is a concern, and right now there are issues (ntp_scale > being the top of the list) however I hope they can be resolved. Looking > at ppc64's do_gettimeofday() vs this implementation there we do have > more overhead, but maybe you could suggest how we can avoid some of it?
I would suggest reclaculating the scale factor and offset for ntp adjustement regulary from the timer tick or so, not on each gettimeofday call. Also, I have some updates to the ppc64 implementation where I regulary update the pre-scale offset into the post-scale one so that the timebase-prescale substraction always gives a 32 bits number. I do that so my fast userland gettimeofday can be implemented more easily and more efficiently for 32 bits processes. I yet have to check how I can hook those things into your new scheme. > I still want to support vsyscall gettimeofday, although it does have to > be done on an arch-by-arch basis. It's likely the systemcfg data > structure can still be generated and exported. I'll look into it and see > what can be done. Well, since it only contains the prescale and postscale offsets and the scaling value, it only needs to be updated when they change, so a hook here would be fine. Ben. - 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/
