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Subject[PATCH] sched: dynamically update the root-domain span/online maps
Date
Hi Steven,
I posted a suspend-to-ram fix to sched-devel earlier today:

http://lkml.org/lkml/2007/12/17/445

This fix should also be applied to -rt as I introduced the same regression
there. Here is a version of the fix for 23-rt13. I can submit a version for
24-rc5-rt1 at your request.

Regards,
-Greg

---------------------------------

The baseline code statically builds the span maps when the domain is formed.
Previous attempts at dynamically updating the maps caused a suspend-to-ram
regression, which should now be fixed.

Signed-off-by: Gregory Haskins <ghaskins@novell.com>
CC: Gautham R Shenoy <ego@in.ibm.com>
---

kernel/sched.c | 28 ++++++++++++++++------------
1 files changed, 16 insertions(+), 12 deletions(-)

diff --git a/kernel/sched.c b/kernel/sched.c
index 244c4b5..95b8c99 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -281,8 +281,6 @@ struct rt_rq {
* exclusive cpuset is created, we also create and attach a new root-domain
* object.
*
- * By default the system creates a single root-domain with all cpus as
- * members (mimicking the global state we have today).
*/
struct root_domain {
atomic_t refcount;
@@ -300,6 +298,10 @@ struct root_domain {
#endif
};

+/*
+ * By default the system creates a single root-domain with all cpus as
+ * members (mimicking the global state we have today).
+ */
static struct root_domain def_root_domain;

#endif
@@ -6066,6 +6068,10 @@ static void rq_attach_root(struct rq *rq, struct root_domain *rd)
atomic_inc(&rd->refcount);
rq->rd = rd;

+ cpu_set(rq->cpu, rd->span);
+ if (cpu_isset(rq->cpu, cpu_online_map))
+ cpu_set(rq->cpu, rd->online);
+
for (class = sched_class_highest; class; class = class->next) {
if (class->join_domain)
class->join_domain(rq);
@@ -6074,12 +6080,12 @@ static void rq_attach_root(struct rq *rq, struct root_domain *rd)
spin_unlock_irqrestore(&rq->lock, flags);
}

-static void init_rootdomain(struct root_domain *rd, const cpumask_t *map)
+static void init_rootdomain(struct root_domain *rd)
{
memset(rd, 0, sizeof(*rd));

- rd->span = *map;
- cpus_and(rd->online, rd->span, cpu_online_map);
+ cpus_clear(rd->span);
+ cpus_clear(rd->online);

cpupri_init(&rd->cpupri);

@@ -6087,13 +6093,11 @@ static void init_rootdomain(struct root_domain *rd, const cpumask_t *map)

static void init_defrootdomain(void)
{
- cpumask_t cpus = CPU_MASK_ALL;
-
- init_rootdomain(&def_root_domain, &cpus);
+ init_rootdomain(&def_root_domain);
atomic_set(&def_root_domain.refcount, 1);
}

-static struct root_domain *alloc_rootdomain(const cpumask_t *map)
+static struct root_domain *alloc_rootdomain(void)
{
struct root_domain *rd;

@@ -6101,7 +6105,7 @@ static struct root_domain *alloc_rootdomain(const cpumask_t *map)
if (!rd)
return NULL;

- init_rootdomain(rd, map);
+ init_rootdomain(rd);

return rd;
}
@@ -6523,7 +6527,7 @@ static int build_sched_domains(const cpumask_t *cpu_map)
sched_group_nodes_bycpu[first_cpu(*cpu_map)] = sched_group_nodes;
#endif

- rd = alloc_rootdomain(cpu_map);
+ rd = alloc_rootdomain();
if (!rd) {
printk(KERN_WARNING "Cannot alloc root domain\n");
return -ENOMEM;
@@ -7021,7 +7025,6 @@ void __init sched_init(void)
#ifdef CONFIG_SMP
rq->sd = NULL;
rq->rd = NULL;
- rq_attach_root(rq, &def_root_domain);
rq->active_balance = 0;
rq->next_balance = jiffies;
rq->push_cpu = 0;
@@ -7030,6 +7033,7 @@ void __init sched_init(void)
INIT_LIST_HEAD(&rq->migration_queue);
rq->rt.highest_prio = MAX_RT_PRIO;
rq->rt.overloaded = 0;
+ rq_attach_root(rq, &def_root_domain);
#endif
atomic_set(&rq->nr_iowait, 0);



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