On Mon, 2 Apr 2007, Thomas Gleixner wrote: > On Mon, 2007-04-02 at 10:30 -0700, Davide Libenzi wrote: > > > > There is no inaccuracy when you rearm the timer on read: hrtimer_forward > > > takes care, that the period is accurate. It does not start the timer out > > > of the periodic order, i.e. on a different time frame. > > > > > > Where is the win of keeping the timer running, when nobody cares about > > > the expiry at all ? It just generates interrupts and events for nothing. > > > > Then you'd lose the ability to know if you lost one or more (yes, you > > could figure it out by reading the time and with a few calculations). I > > think that the capping (to a sane value) idea solves the DoS issue and at > > the same time have the ability to report you missed ticks. What are your > > strong points against that solution? > > Err, the read function > > ticks = hrtimer_forward(&ctx->tmr, ktime_get(), > ctx->tintv); > > does give you the number of (lost) ticks. > > tmr->expires holds the absolute expiry time of the last event. > hrtimer_forward() adds N intervals to tmr->expires, so that the new > tmr->expires value is greater than now (ktime_get()). It returns N. > > So the number of lost ticks is N - 1. No time reading and no magic > math :)
Yack, I missed that part :) Sounds fine then. - Davide - 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/
