Messages in this thread | | | Date | Wed, 3 Jun 2015 07:37:49 +0100 | From | Alexander Gordeev <> | Subject | Re: [PATCH 2/2] rcu: Simplify rcu_init_geometry() capacity arithmetics |
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On Wed, Jun 03, 2015 at 08:18:33AM +0200, Alexander Gordeev wrote: > Current code suggests that introducing the extra level to > rcu_capacity[] array makes some of the arithmetic easier. > Well, in fact it appears rather confusing and unnecessary.
Please, ignore this one.
> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> > Signed-off-by: Alexander Gordeev <agordeev@redhat.com> > --- > kernel/rcu/tree.c | 16 +++++++--------- > 1 file changed, 7 insertions(+), 9 deletions(-) > > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c > index 0e8c24d..e6ddd20 100644 > --- a/kernel/rcu/tree.c > +++ b/kernel/rcu/tree.c > @@ -4038,7 +4038,7 @@ static void __init rcu_init_geometry(void) > { > ulong d; > int i; > - int rcu_capacity[MAX_RCU_LVLS + 1]; > + int rcu_capacity[MAX_RCU_LVLS]; > > /* > * Initialize any unspecified boot parameters. > @@ -4062,12 +4062,10 @@ static void __init rcu_init_geometry(void) > > /* > * Compute number of nodes that can be handled an rcu_node tree > - * with the given number of levels. Setting rcu_capacity[0] makes > - * some of the arithmetic easier. > + * with the given number of levels. > */ > - rcu_capacity[0] = 1; > - rcu_capacity[1] = rcu_fanout_leaf; > - for (i = 2; i <= MAX_RCU_LVLS; i++) > + rcu_capacity[0] = rcu_fanout_leaf; > + for (i = 1; i < MAX_RCU_LVLS; i++) > rcu_capacity[i] = rcu_capacity[i - 1] * CONFIG_RCU_FANOUT; > > /* > @@ -4080,7 +4078,7 @@ static void __init rcu_init_geometry(void) > * the rcu_node masks. Complain and fall back to the compile- > * time values if these limits are exceeded. > */ > - if (nr_cpu_ids > rcu_capacity[MAX_RCU_LVLS]) > + if (nr_cpu_ids > rcu_capacity[MAX_RCU_LVLS - 1]) > panic("rcu_init_geometry: rcu_capacity[] is too small"); > else if (rcu_fanout_leaf < CONFIG_RCU_FANOUT_LEAF || > rcu_fanout_leaf > sizeof(unsigned long) * 8) { > @@ -4091,11 +4089,11 @@ static void __init rcu_init_geometry(void) > /* Calculate the number of levels in the tree. */ > for (i = 1; nr_cpu_ids > rcu_capacity[i]; i++) { > } > - rcu_num_lvls = i; > + rcu_num_lvls = i + 1; > > /* Calculate the number of rcu_nodes at each level of the tree. */ > for (i = 0; i < rcu_num_lvls; i++) { > - int cap = rcu_capacity[rcu_num_lvls - i]; > + int cap = rcu_capacity[(rcu_num_lvls - 1) - i]; > num_rcu_lvl[i] = DIV_ROUND_UP(nr_cpu_ids, cap); > } > > -- > 1.8.3.1 >
-- Regards, Alexander Gordeev agordeev@redhat.com
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