[tip:sched/domains] sched: Simplify finding the lowest sched_domain

From: tip-bot for Peter Zijlstra
Date: Mon Apr 11 2011 - 10:37:35 EST


Commit-ID: 21d42ccfd6c6c11f96c2acfd32a85cfc33514d3a
Gitweb: http://git.kernel.org/tip/21d42ccfd6c6c11f96c2acfd32a85cfc33514d3a
Author: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
AuthorDate: Thu, 7 Apr 2011 14:09:48 +0200
Committer: Ingo Molnar <mingo@xxxxxxx>
CommitDate: Mon, 11 Apr 2011 12:58:19 +0200

sched: Simplify finding the lowest sched_domain

Instead of relying on knowing the build order and various CONFIG_
flags simply remember the bottom most sched_domain when we created the
domain hierarchy.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Mike Galbraith <efault@xxxxxx>
Cc: Nick Piggin <npiggin@xxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/20110407122942.134511046@xxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
---
kernel/sched.c | 23 +++++++++++++----------
1 files changed, 13 insertions(+), 10 deletions(-)

diff --git a/kernel/sched.c b/kernel/sched.c
index e66d24a..d6992bf 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -6865,11 +6865,13 @@ struct s_data {
cpumask_var_t nodemask;
cpumask_var_t send_covered;
cpumask_var_t tmpmask;
+ struct sched_domain ** __percpu sd;
struct root_domain *rd;
};

enum s_alloc {
sa_rootdomain,
+ sa_sd,
sa_tmpmask,
sa_send_covered,
sa_nodemask,
@@ -7104,6 +7106,8 @@ static void __free_domain_allocs(struct s_data *d, enum s_alloc what,
switch (what) {
case sa_rootdomain:
free_rootdomain(d->rd); /* fall through */
+ case sa_sd:
+ free_percpu(d->sd); /* fall through */
case sa_tmpmask:
free_cpumask_var(d->tmpmask); /* fall through */
case sa_send_covered:
@@ -7124,10 +7128,15 @@ static enum s_alloc __visit_domain_allocation_hell(struct s_data *d,
return sa_nodemask;
if (!alloc_cpumask_var(&d->tmpmask, GFP_KERNEL))
return sa_send_covered;
+ d->sd = alloc_percpu(struct sched_domain *);
+ if (!d->sd) {
+ printk(KERN_WARNING "Cannot alloc per-cpu pointers\n");
+ return sa_tmpmask;
+ }
d->rd = alloc_rootdomain();
if (!d->rd) {
printk(KERN_WARNING "Cannot alloc root domain\n");
- return sa_tmpmask;
+ return sa_sd;
}
return sa_rootdomain;
}
@@ -7316,6 +7325,8 @@ static int __build_sched_domains(const struct cpumask *cpu_map,
sd = __build_mc_sched_domain(&d, cpu_map, attr, sd, i);
sd = __build_smt_sched_domain(&d, cpu_map, attr, sd, i);

+ *per_cpu_ptr(d.sd, i) = sd;
+
for (tmp = sd; tmp; tmp = tmp->parent) {
tmp->span_weight = cpumask_weight(sched_domain_span(tmp));
build_sched_groups(&d, tmp, cpu_map, i);
@@ -7363,15 +7374,7 @@ static int __build_sched_domains(const struct cpumask *cpu_map,

/* Attach the domains */
for_each_cpu(i, cpu_map) {
-#ifdef CONFIG_SCHED_SMT
- sd = &per_cpu(cpu_domains, i).sd;
-#elif defined(CONFIG_SCHED_MC)
- sd = &per_cpu(core_domains, i).sd;
-#elif defined(CONFIG_SCHED_BOOK)
- sd = &per_cpu(book_domains, i).sd;
-#else
- sd = &per_cpu(phys_domains, i).sd;
-#endif
+ sd = *per_cpu_ptr(d.sd, i);
cpu_attach_domain(sd, d.rd, i);
}

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