From mboxrd@z Thu Jan 1 00:00:00 1970 From: Quentin Perret Subject: [PATCH v6 06/14] sched/topology: Lowest CPU asymmetry sched_domain level pointer Date: Mon, 20 Aug 2018 10:44:12 +0100 Message-ID: <20180820094420.26590-7-quentin.perret@arm.com> References: <20180820094420.26590-1-quentin.perret@arm.com> Return-path: In-Reply-To: <20180820094420.26590-1-quentin.perret@arm.com> Sender: linux-kernel-owner@vger.kernel.org To: peterz@infradead.org, rjw@rjwysocki.net, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org Cc: gregkh@linuxfoundation.org, mingo@redhat.com, dietmar.eggemann@arm.com, morten.rasmussen@arm.com, chris.redpath@arm.com, patrick.bellasi@arm.com, valentin.schneider@arm.com, vincent.guittot@linaro.org, thara.gopinath@linaro.org, viresh.kumar@linaro.org, tkjos@google.com, joel@joelfernandes.org, smuckle@google.com, adharmap@codeaurora.org, skannan@codeaurora.org, pkondeti@codeaurora.org, juri.lelli@redhat.com, edubezval@gmail.com, srinivas.pandruvada@linux.intel.com, currojerez@riseup.net, javi.merino@kernel.org, quentin.perret@arm.com List-Id: linux-pm@vger.kernel.org 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. Cross-sockets wake-up balancing will only happen when the system is over-utilized, or this_cpu and prev_cpu are in different sockets. cc: Ingo Molnar cc: Peter Zijlstra Suggested-by: Morten Rasmussen Signed-off-by: Quentin Perret --- 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 c60616796483..c28c7adcc7b3 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -9167,7 +9167,7 @@ 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 97d79429e755..4b884e467545 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -1203,7 +1203,8 @@ 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 545e2c7b6e66..4c6a36a8d7b8 100644 --- a/kernel/sched/topology.c +++ b/kernel/sched/topology.c @@ -508,7 +508,8 @@ 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) @@ -534,7 +535,10 @@ 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); } /* -- 2.17.1