Messages in this thread | | | Date | Wed, 3 Mar 2010 18:00:14 +0100 | From | Fabio Checconi <> | Subject | Re: [PATCH 2/3] sched: enforce per-cpu utilization limits on runtime balancing |
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> From: Peter Zijlstra <peterz@infradead.org> > Date: Thu, Feb 25, 2010 09:28:23PM +0100 > > On Tue, 2010-02-23 at 19:56 +0100, Fabio Checconi wrote: > > +#ifdef CONFIG_SMP > > +static inline unsigned long rt_init_free_bw(void) > > +{ > > + unsigned long used = to_ratio(global_rt_period(), global_rt_runtime()); > > + > > + return to_ratio(RUNTIME_INF, RUNTIME_INF) - used; > > +} > > +#endif > > > +static void __rt_restart_balancing(void) > > +{ > > + unsigned long used, global, free; > > + struct rq *rq; > > + int i; > > + > > + used = rt_used_bandwidth(); > > + global = to_ratio(RUNTIME_INF, RUNTIME_INF); > > + > > + free = global - used; > > > We take the max as RUNTIME_INF instead of global_rt_* so that we can > move runtime around and fully saturate a single cpu (given there is > enough free to compensate on other cpus) ?
The only reason I've used RUNTIME_INF instead of global_rt_* is for the !GROUP_SCHED case, where using the global_rt_* values would make balancing have no effect at all (the initial value for def_rt_bandwidth already uses the maximum bw on each cpu) . The current throttling implementation in this case still tries to concentrate bw on a single cpu, and I wanted to replicate the same behaviour.
Should I go for the global_rt_* values and add some #ifdef unreadability to avoid the balancing overhead in the !GROUP_SCHED case?
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