On Thu, Jun 16, 2016 at 09:02:15AM -0700, Paul E. McKenney wrote: > > 2) When we do that right, we can make the tick frequency a command line > > option > > and just have a compiled in default. > > As long as there is something that tells RCU what the tick frequency > actually is at runtime, this should not be a problem. For example, > in rcu_implicit_dynticks_qs(), the following: > > rdp->rsp->jiffies_resched += 5; > > Would instead need to be something like: > > rdp->rsp->jiffies_resched += 5 * jiffies_per_tick; > > Changing tick frequency at runtime would be a bit more tricky, as it would > be tough to avoid some oddball false positives during the transition.
So the 'fun' part will be frequencies with non integer factors of 1000. Like say HZ=300. For that we'll have to keep jiffies_remainder, and add an extra jiffy every time that rolls over. That would make your case slightly more interesting than you really want I suspect.
