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Subject[tip:sched/domains] sched: Avoid allocations in sched_domain_debug()
Commit-ID:  4cb988395da6e16627a8be69729e50cd72ebb23e
Gitweb: http://git.kernel.org/tip/4cb988395da6e16627a8be69729e50cd72ebb23e
Author: Peter Zijlstra <a.p.zijlstra@chello.nl>
AuthorDate: Thu, 7 Apr 2011 14:09:58 +0200
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Mon, 11 Apr 2011 14:05:00 +0200

sched: Avoid allocations in sched_domain_debug()

Since we're all serialized by sched_domains_mutex we can use
sched_domains_tmpmask and avoid having to do allocations. This means
we can use sched_domains_debug() for cpu_attach_domain() again.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Nick Piggin <npiggin@kernel.dk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20110407122942.664347467@chello.nl
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
kernel/sched.c | 17 +++++------------
1 files changed, 5 insertions(+), 12 deletions(-)

diff --git a/kernel/sched.c b/kernel/sched.c
index fd73e91..35fc995 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -6395,6 +6395,8 @@ early_initcall(migration_init);

#ifdef CONFIG_SMP

+static cpumask_var_t sched_domains_tmpmask; /* sched_domains_mutex */
+
#ifdef CONFIG_SCHED_DEBUG

static __read_mostly int sched_domain_debug_enabled;
@@ -6490,7 +6492,6 @@ static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level,

static void sched_domain_debug(struct sched_domain *sd, int cpu)
{
- cpumask_var_t groupmask;
int level = 0;

if (!sched_domain_debug_enabled)
@@ -6503,20 +6504,14 @@ static void sched_domain_debug(struct sched_domain *sd, int cpu)

printk(KERN_DEBUG "CPU%d attaching sched-domain:\n", cpu);

- if (!alloc_cpumask_var(&groupmask, GFP_KERNEL)) {
- printk(KERN_DEBUG "Cannot load-balance (out of memory)\n");
- return;
- }
-
for (;;) {
- if (sched_domain_debug_one(sd, cpu, level, groupmask))
+ if (sched_domain_debug_one(sd, cpu, level, sched_domains_tmpmask))
break;
level++;
sd = sd->parent;
if (!sd)
break;
}
- free_cpumask_var(groupmask);
}
#else /* !CONFIG_SCHED_DEBUG */
# define sched_domain_debug(sd, cpu) do { } while (0)
@@ -6721,7 +6716,7 @@ cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu)
sd->child = NULL;
}

- /* sched_domain_debug(sd, cpu); */
+ sched_domain_debug(sd, cpu);

rq_attach_root(rq, rd);
tmp = rq->sd;
@@ -6851,8 +6846,6 @@ static int get_group(int cpu, struct sd_data *sdd, struct sched_group **sg)
return cpu;
}

-static cpumask_var_t sched_domains_tmpmask; /* sched_domains_mutex */
-
/*
* build_sched_groups takes the cpumask we wish to span, and a pointer
* to a function which identifies what group(along with sched group) a CPU
@@ -7896,8 +7889,8 @@ void __init sched_init(void)

/* Allocate the nohz_cpu_mask if CONFIG_CPUMASK_OFFSTACK */
zalloc_cpumask_var(&nohz_cpu_mask, GFP_NOWAIT);
- zalloc_cpumask_var(&sched_domains_tmpmask, GFP_NOWAIT);
#ifdef CONFIG_SMP
+ zalloc_cpumask_var(&sched_domains_tmpmask, GFP_NOWAIT);
#ifdef CONFIG_NO_HZ
zalloc_cpumask_var(&nohz.idle_cpus_mask, GFP_NOWAIT);
alloc_cpumask_var(&nohz.grp_idle_mask, GFP_NOWAIT);

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