From: Quentin Perret <quentin.per...@arm.com> [ Upstream commit 011b27bb5d3139e8b5fe9ceff1fc7f6dc3145071 ]
Add another member to the family of per-cpu sched_domain shortcut pointers. This one, sd_asym_cpucapacity, points to the lowest level at which the SD_ASYM_CPUCAPACITY flag is set. While at it, rename the sd_asym shortcut to sd_asym_packing to avoid confusions. Generally speaking, the largest opportunity to save energy via scheduling comes from a smarter exploitation of heterogeneous platforms (i.e. big.LITTLE). Consequently, the sd_asym_cpucapacity shortcut will be used at first as the lowest domain where Energy-Aware Scheduling (EAS) should be applied. For example, it is possible to apply EAS within a socket on a multi-socket system, as long as each socket has an asymmetric topology. Energy-aware cross-sockets wake-up balancing will only happen when the system is over-utilized, or this_cpu and prev_cpu are in different sockets. Suggested-by: Morten Rasmussen <morten.rasmus...@arm.com> Signed-off-by: Quentin Perret <quentin.per...@arm.com> Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Mike Galbraith <efa...@gmx.de> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Thomas Gleixner <t...@linutronix.de> Cc: adhar...@codeaurora.org Cc: chris.redp...@arm.com Cc: curroje...@riseup.net Cc: dietmar.eggem...@arm.com Cc: edubez...@gmail.com Cc: gre...@linuxfoundation.org Cc: javi.mer...@kernel.org Cc: j...@joelfernandes.org Cc: juri.le...@redhat.com Cc: patrick.bell...@arm.com Cc: pkond...@codeaurora.org Cc: r...@rjwysocki.net Cc: skan...@codeaurora.org Cc: smuc...@google.com Cc: srinivas.pandruv...@linux.intel.com Cc: thara.gopin...@linaro.org Cc: tk...@google.com Cc: valentin.schnei...@arm.com Cc: vincent.guit...@linaro.org Cc: viresh.ku...@linaro.org Link: https://lkml.kernel.org/r/20181203095628.11858-7-quentin.per...@arm.com Signed-off-by: Ingo Molnar <mi...@kernel.org> Signed-off-by: Sasha Levin <sas...@kernel.org> --- kernel/sched/fair.c | 2 +- kernel/sched/sched.h | 3 ++- kernel/sched/topology.c | 8 ++++++-- 3 files changed, 9 insertions(+), 4 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index e8f191ba3fe5..9ef0b878229d 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -9256,7 +9256,7 @@ static void nohz_balancer_kick(struct rq *rq) } } - sd = rcu_dereference(per_cpu(sd_asym, cpu)); + sd = rcu_dereference(per_cpu(sd_asym_packing, cpu)); if (sd) { for_each_cpu(i, sched_domain_span(sd)) { if (i == cpu || diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 4e524ab589c9..6f68dcb791f6 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -1285,7 +1285,8 @@ DECLARE_PER_CPU(int, sd_llc_size); DECLARE_PER_CPU(int, sd_llc_id); DECLARE_PER_CPU(struct sched_domain_shared *, sd_llc_shared); DECLARE_PER_CPU(struct sched_domain *, sd_numa); -DECLARE_PER_CPU(struct sched_domain *, sd_asym); +DECLARE_PER_CPU(struct sched_domain *, sd_asym_packing); +DECLARE_PER_CPU(struct sched_domain *, sd_asym_cpucapacity); extern struct static_key_false sched_asym_cpucapacity; struct sched_group_capacity { diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c index 8d7f15ba5916..ced83d060ec8 100644 --- a/kernel/sched/topology.c +++ b/kernel/sched/topology.c @@ -397,7 +397,8 @@ DEFINE_PER_CPU(int, sd_llc_size); DEFINE_PER_CPU(int, sd_llc_id); DEFINE_PER_CPU(struct sched_domain_shared *, sd_llc_shared); DEFINE_PER_CPU(struct sched_domain *, sd_numa); -DEFINE_PER_CPU(struct sched_domain *, sd_asym); +DEFINE_PER_CPU(struct sched_domain *, sd_asym_packing); +DEFINE_PER_CPU(struct sched_domain *, sd_asym_cpucapacity); DEFINE_STATIC_KEY_FALSE(sched_asym_cpucapacity); static void update_top_cache_domain(int cpu) @@ -423,7 +424,10 @@ static void update_top_cache_domain(int cpu) rcu_assign_pointer(per_cpu(sd_numa, cpu), sd); sd = highest_flag_domain(cpu, SD_ASYM_PACKING); - rcu_assign_pointer(per_cpu(sd_asym, cpu), sd); + rcu_assign_pointer(per_cpu(sd_asym_packing, cpu), sd); + + sd = lowest_flag_domain(cpu, SD_ASYM_CPUCAPACITY); + rcu_assign_pointer(per_cpu(sd_asym_cpucapacity, cpu), sd); } /* -- 2.19.1
