On Fri, 2013-02-08 at 16:53 +0100, Frederic Weisbecker wrote: > 2013/2/7 Christoph Lameter <c...@linux.com>: > > On Thu, 7 Feb 2013, Frederic Weisbecker wrote: > > > >> Not with hrtick. > > > > hrtick? Did we not already try that a couple of years back and it turned > > out that the overhead of constantly reprogramming a timer via the PCI bus > > was causing too much of a performance regression? > > Yeah Peter said that especially reprogramming the clock everytime we > call schedule() was killing the performances. Now may be on some > workloads, with the tick stopped, we can find some new results.
I could imagine this being dynamic. If the system isn't very loaded, and the scheduler is giving lots of time slices to tasks, then perhaps it could switch to a reprogramming the clock based scheduling. Or maybe, we could switch to a "skip ticks" method. That is, instead of completely disabling the tick, make the tick go off every other time or less, and use the NO_HZ code to calculate the missed ticks. -- Steve -- 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/