sched: Remove stale power aware scheduling remnants and dysfunctional knobs

It's been broken forever (i.e. it's not scheduling in a power
aware fashion), as reported by Suresh and others sending
patches, and nobody cares enough to fix it properly ...
so remove it to make space free for something better.

There's various problems with the code as it stands today, first
and foremost the user interface which is bound to topology
levels and has multiple values per level. This results in a
state explosion which the administrator or distro needs to
master and almost nobody does.

Furthermore large configuration state spaces aren't good, it
means the thing doesn't just work right because it's either
under so many impossibe to meet constraints, or even if
there's an achievable state workloads have to be aware of
it precisely and can never meet it for dynamic workloads.

So pushing this kind of decision to user-space was a bad idea
even with a single knob - it's exponentially worse with knobs
on every node of the topology.

There is a proposal to replace the user interface with a single
3 state knob:

 sched_balance_policy := { performance, power, auto }

where 'auto' would be the preferred default which looks at things
like Battery/AC mode and possible cpufreq state or whatever the hw
exposes to show us power use expectations - but there's been no
progress on it in the past many months.

Aside from that, the actual implementation of the various knobs
is known to be broken. There have been sporadic attempts at
fixing things but these always stop short of reaching a mergable
state.

Therefore this wholesale removal with the hopes of spurring
people who care to come forward once again and work on a
coherent replacement.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/1326104915.2442.53.camel@twins
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 0 insertions, 94 deletions

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index bd314d7cd9f8..24ca677b5457 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -5929,8 +5929,6 @@ static const struct cpumask *cpu_cpu_mask(int cpu)
 	return cpumask_of_node(cpu_to_node(cpu));
 }
 
-int sched_smt_power_savings = 0, sched_mc_power_savings = 0;
-
 struct sd_data {
 	struct sched_domain **__percpu sd;
 	struct sched_group **__percpu sg;
@@ -6322,7 +6320,6 @@ sd_numa_init(struct sched_domain_topology_level *tl, int cpu)
 					| 0*SD_WAKE_AFFINE
 					| 0*SD_PREFER_LOCAL
 					| 0*SD_SHARE_CPUPOWER
-					| 0*SD_POWERSAVINGS_BALANCE
 					| 0*SD_SHARE_PKG_RESOURCES
 					| 1*SD_SERIALIZE
 					| 0*SD_PREFER_SIBLING
@@ -6819,97 +6816,6 @@ match2:
 	mutex_unlock(&sched_domains_mutex);
 }
 
-#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
-static void reinit_sched_domains(void)
-{
-	get_online_cpus();
-
-	/* Destroy domains first to force the rebuild */
-	partition_sched_domains(0, NULL, NULL);
-
-	rebuild_sched_domains();
-	put_online_cpus();
-}
-
-static ssize_t sched_power_savings_store(const char *buf, size_t count, int smt)
-{
-	unsigned int level = 0;
-
-	if (sscanf(buf, "%u", &level) != 1)
-		return -EINVAL;
-
-	/*
-	 * level is always be positive so don't check for
-	 * level < POWERSAVINGS_BALANCE_NONE which is 0
-	 * What happens on 0 or 1 byte write,
-	 * need to check for count as well?
-	 */
-
-	if (level >= MAX_POWERSAVINGS_BALANCE_LEVELS)
-		return -EINVAL;
-
-	if (smt)
-		sched_smt_power_savings = level;
-	else
-		sched_mc_power_savings = level;
-
-	reinit_sched_domains();
-
-	return count;
-}
-
-#ifdef CONFIG_SCHED_MC
-static ssize_t sched_mc_power_savings_show(struct device *dev,
-					   struct device_attribute *attr,
-					   char *buf)
-{
-	return sprintf(buf, "%u\n", sched_mc_power_savings);
-}
-static ssize_t sched_mc_power_savings_store(struct device *dev,
-					    struct device_attribute *attr,
-					    const char *buf, size_t count)
-{
-	return sched_power_savings_store(buf, count, 0);
-}
-static DEVICE_ATTR(sched_mc_power_savings, 0644,
-		   sched_mc_power_savings_show,
-		   sched_mc_power_savings_store);
-#endif
-
-#ifdef CONFIG_SCHED_SMT
-static ssize_t sched_smt_power_savings_show(struct device *dev,
-					    struct device_attribute *attr,
-					    char *buf)
-{
-	return sprintf(buf, "%u\n", sched_smt_power_savings);
-}
-static ssize_t sched_smt_power_savings_store(struct device *dev,
-					    struct device_attribute *attr,
-					     const char *buf, size_t count)
-{
-	return sched_power_savings_store(buf, count, 1);
-}
-static DEVICE_ATTR(sched_smt_power_savings, 0644,
-		   sched_smt_power_savings_show,
-		   sched_smt_power_savings_store);
-#endif
-
-int __init sched_create_sysfs_power_savings_entries(struct device *dev)
-{
-	int err = 0;
-
-#ifdef CONFIG_SCHED_SMT
-	if (smt_capable())
-		err = device_create_file(dev, &dev_attr_sched_smt_power_savings);
-#endif
-#ifdef CONFIG_SCHED_MC
-	if (!err && mc_capable())
-		err = device_create_file(dev, &dev_attr_sched_mc_power_savings);
-#endif
-	return err;
-}
-#endif /* CONFIG_SCHED_MC || CONFIG_SCHED_SMT */
-
 /*
  * Update cpusets according to cpu_active mask.  If cpusets are
  * disabled, cpuset_update_active_cpus() becomes a simple wrapper