Messages in this thread | | | Date | Thu, 16 Jun 2016 17:40:51 -0700 | From | "Paul E. McKenney" <> | Subject | Re: [patch 13/20] timer: Switch to a non cascading wheel |
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On Thu, Jun 16, 2016 at 08:14:02PM +0200, Peter Zijlstra wrote: > 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.
My particular case is not that sensitive, so 1000/300 would be plenty accurate.
Thanx, Paul
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