Messages in this thread |  | | | Date | Fri, 22 Aug 2008 06:47:20 -0700 | | From | "Paul E. McKenney" <> | | Subject | Re: [PATCH, RFC, tip/core/rcu] scalable classic RCU implementation | |
On Fri, Aug 22, 2008 at 06:37:15AM +0200, Ingo Molnar wrote:
>
> * Paul E. McKenney <paulmck@linux.vnet.ibm.com> wrote:
>
> > +#define MAX_RCU_LEVELS 3
> > +#if NR_CPUS <= CONFIG_RCU_FANOUT
> > +#define NUM_RCU_LEVELS 1
> > +#define NUM_RCU_LEVEL_1 1
> > +#define NUM_RCU_LEVEL_2 NR_CPUS
> > +#define NUM_RCU_LEVEL_3 0
> > +#define NUM_RCU_LEVEL_4 0
> > +#define NUM_RCU_NODES NUM_RCU_LEVEL_1
> > +#elif NR_CPUS <= CONFIG_RCU_FANOUT * CONFIG_RCU_FANOUT
> > +#define NUM_RCU_LEVELS 2
> > +#define NUM_RCU_LEVEL_1 1
> > +#define NUM_RCU_LEVEL_2 \
> > + (((NR_CPUS) + (CONFIG_RCU_FANOUT) - 1) / (CONFIG_RCU_FANOUT))
> > +#define NUM_RCU_LEVEL_3 NR_CPUS
> > +#define NUM_RCU_LEVEL_4 0
> > +#define NUM_RCU_NODES \
> > + ((NUM_RCU_LEVEL_1) + (NUM_RCU_LEVEL_2))
> > +#elif NR_CPUS <= CONFIG_RCU_FANOUT * CONFIG_RCU_FANOUT * CONFIG_RCU_FANOUT
> > +#define NUM_RCU_LEVELS 3
> > +#define RCU_FANOUT_SQ ((CONFIG_RCU_FANOUT) * (CONFIG_RCU_FANOUT))
> > +#define NUM_RCU_LEVEL_1 1
> > +#define NUM_RCU_LEVEL_2 \
> > + (((NR_CPUS) + (RCU_FANOUT_SQ) - 1) / (RCU_FANOUT_SQ))
> > +#define NUM_RCU_LEVEL_3 \
> > + ((NR_CPUS) + (CONFIG_RCU_FANOUT) - 1) / (CONFIG_RCU_FANOUT)
> > +#define NUM_RCU_LEVEL_4 NR_CPUS
> > +#define NUM_RCU_NODES \
> > + ((NUM_RCU_LEVEL_1) + \
> > + (NUM_RCU_LEVEL_2) + \
> > + (NUM_RCU_LEVEL_3))
> > +#else
> > +#error "CONFIG_RCU_FANOUT insufficient for NR_CPUS"
> > +#endif
>
> just a quick stylistic suggestion: if feasible then such sizing ugliness
> should be hidden in a Kconfig file. (if Kconfig is capable enough for
> this that is)
I have no idea if Kconfig can do it, but I will check.
Thanx, Paul
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