On Tue, 6 Dec 2016 15:20:55 +1100 Paul Mackerras <pau...@ozlabs.org> wrote:
> On Tue, Dec 06, 2016 at 03:32:13AM +0100, Frederic Weisbecker wrote: > > This follows up Martin Schwidefsky's patch which propose to delay > > cputime accounting to the tick in order to minimize the calls to > > account_system_time() and alikes as these functions can carry quite some > > overhead: > > > > http://lkml.kernel.org/r/20161121111728.13a0a3db@mschwide > > > > The set includes Martin's patch, rebased on top of tip:sched/core and > > latest s390 changes, and extends it to the other implementations of > > CONFIG_VIRT_CPU_ACCOUNTING_NATIVE (powerpc and ia64) along with a few > > core changes to adapt the whole. > > > > Only built-tested though as I don't have access to any of these archs. > > The patches look reasonable at a quick look. I assume that to test > them, we would want to run a guest in an overcommitted system, so as > to get some steal time. Do you have any more specific suggestions as > to what to run as a test? Just run some benchmark and see if the > user/system/irq times look reasonable? Or do you have something more > quantitative? My quick test this morning showed that for s390 it works quite well. I yet have to do more detailed tests to see if the numbers really add up. -- blue skies, Martin. "Reality continues to ruin my life." - Calvin.
