diff options
Diffstat (limited to 'meta-eas/recipes-kernel/linux/linux-renesas/0049-sched-EAS-cpu-hotplug-interoperability.patch')
| -rw-r--r-- | meta-eas/recipes-kernel/linux/linux-renesas/0049-sched-EAS-cpu-hotplug-interoperability.patch | 204 |
1 files changed, 204 insertions, 0 deletions
diff --git a/meta-eas/recipes-kernel/linux/linux-renesas/0049-sched-EAS-cpu-hotplug-interoperability.patch b/meta-eas/recipes-kernel/linux/linux-renesas/0049-sched-EAS-cpu-hotplug-interoperability.patch new file mode 100644 index 0000000..447e302 --- /dev/null +++ b/meta-eas/recipes-kernel/linux/linux-renesas/0049-sched-EAS-cpu-hotplug-interoperability.patch @@ -0,0 +1,204 @@ +From 3477712d21ac713611aa74f9f5a6ff4b1e49a930 Mon Sep 17 00:00:00 2001 +From: Dietmar Eggemann <dietmar.eggemann@arm.com> +Date: Thu, 30 Jul 2015 16:53:30 +0100 +Subject: [PATCH 49/92] sched: EAS & cpu hotplug interoperability + +For Energy-Aware Scheduling (EAS) to work properly, even in the case that +cpus are hot-plugged out, the energy model (EM) data on all energy-aware +sched domains has to be present for all online cpus. + +Mainline sd hierarchy setup code will remove sd's which are not useful for +task scheduling e.g. in the following situations: + +1. Only one cpu remains in one cluster of a two cluster system. + + This remaining cpu only has DIE and no MC sd. + +2. A complete cluster in a two-cluster system is hot-plugged out. + + The cpus of the remaining cluster only have MC and no DIE sd. + +To make sure that all online cpus keep all their energy-aware sd's, +the sd degenerate functionality has been changed to not free sd's if +their first sg contains EM data in case: + +1. There is only one cpu left in the sd. + +2. There have to be at least 2 sg's if certain sd flags are set. + +Instead of freeing such an sd it now clears only its SD_LOAD_BALANCE +flag. + +This will make sure that the EAS functionality will always see all +energy-aware sd's for all online cpus. + +It will introduce a (small ?) performance degradation since the +hot-path macro for_each_domain() has to deal with sd's not +contributing to task-scheduling at all now. There is the handling +of newidle decay values before the SD_LOAD_BALANCE check in +rebalance_domains(). +But generally, code to make sure that task scheduling is not invoked +on these sd's is in place (if (!(sd->flags & SD_LOAD_BALANCE)) +already. + +This patch has been tested on a single (a7) cluster TC2 system. I.e. we +could abandon the SYS sd level patch and use this patch to solve all +problems related to sd topology setups and runtime changes. + +This patch should not be squashed. + +Test (w/ CONFIG_SCHED_DEBUG): + +JUNO: + +$ cat /proc/cpuinfo | grep "^CPU part" +CPU part : 0xd03 +CPU part : 0xd07 +CPU part : 0xd07 +CPU part : 0xd03 +CPU part : 0xd03 +CPU part : 0xd03 + +$ cat /proc/sys/kernel/sched_domain/cpu*/domain*/{name,flags} + +MC +DIE +MC +DIE +MC +DIE +MC +DIE +MC +DIE +MC +DIE +33583 - 0x832f +4143 - 0x102f +33583 +4143 +33583 +4143 +33583 +4143 +33583 +4143 +33583 +4143 + +Hotplug-out A57 cluster + +$ echo 0 > /sys/devices/system/cpu/cpu1/online +$ echo 0 > /sys/devices/system/cpu/cpu2/online + +$ cat /proc/sys/kernel/sched_domain/cpu*/domain*/{name,flags} + +MC +DIE +MC +DIE +MC +DIE +MC +DIE +33583 +4142 - 0x102e <-- !SD_LOAD_BALANCE +33583 +4142 +33583 +4142 +33583 +4142 + +Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com> +(cherry picked from commit a5ebdd0fe5357fe125d9603d766adc69e7607981) +Signed-off-by: Gaku Inami <gaku.inami.xw@bp.renesas.com> +--- + kernel/sched/core.c | 17 ++++++++++------- + kernel/sched/fair.c | 7 +++++-- + 2 files changed, 15 insertions(+), 9 deletions(-) + +diff --git a/kernel/sched/core.c b/kernel/sched/core.c +index 083b318..f31ea62 100644 +--- a/kernel/sched/core.c ++++ b/kernel/sched/core.c +@@ -5663,9 +5663,6 @@ static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level, + + if (!(sd->flags & SD_LOAD_BALANCE)) { + printk("does not load-balance\n"); +- if (sd->parent) +- printk(KERN_ERR "ERROR: !SD_LOAD_BALANCE domain" +- " has parent"); + return -1; + } + +@@ -5760,8 +5757,12 @@ static inline bool sched_debug(void) + + static int sd_degenerate(struct sched_domain *sd) + { +- if (cpumask_weight(sched_domain_span(sd)) == 1) +- return 1; ++ if (cpumask_weight(sched_domain_span(sd)) == 1) { ++ if (sd->groups->sge) ++ sd->flags &= ~SD_LOAD_BALANCE; ++ else ++ return 1; ++ } + + /* Following flags need at least 2 groups */ + if (sd->flags & (SD_LOAD_BALANCE | +@@ -5805,6 +5806,10 @@ static int sd_degenerate(struct sched_domain *sd) + SD_SHARE_PKG_RESOURCES | + SD_PREFER_SIBLING | + SD_SHARE_POWERDOMAIN); ++ if (parent->groups->sge) { ++ parent->flags &= ~SD_LOAD_BALANCE; ++ return 0; ++ } + if (nr_node_ids == 1) + pflags &= ~SD_SERIALIZE; + } +@@ -7098,8 +7103,6 @@ static int build_sched_domains(const struct cpumask *cpu_map, + *per_cpu_ptr(d.sd, i) = sd; + if (tl->flags & SDTL_OVERLAP || sched_feat(FORCE_SD_OVERLAP)) + sd->flags |= SD_OVERLAP; +- if (cpumask_equal(cpu_map, sched_domain_span(sd))) +- break; + } + } + +diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c +index fa393d9..c7d9bbf 100644 +--- a/kernel/sched/fair.c ++++ b/kernel/sched/fair.c +@@ -7457,6 +7457,9 @@ static inline enum fbq_type fbq_classify_rq(struct rq *rq) + } + #endif /* CONFIG_NUMA_BALANCING */ + ++#define lb_sd_parent(sd) \ ++ (sd->parent && sd->parent->groups != sd->parent->groups->next) ++ + /** + * update_sd_lb_stats - Update sched_domain's statistics for load balancing. + * @env: The load balancing environment. +@@ -7530,7 +7533,7 @@ static inline void update_sd_lb_stats(struct lb_env *env, struct sd_lb_stats *sd + + env->src_grp_nr_running = sds->busiest_stat.sum_nr_running; + +- if (!env->sd->parent) { ++ if (!lb_sd_parent(env->sd)) { + /* update overload indicator if we are at root domain */ + if (env->dst_rq->rd->overload != overload) + env->dst_rq->rd->overload = overload; +@@ -7989,7 +7992,7 @@ static int load_balance(int this_cpu, struct rq *this_rq, + int *continue_balancing) + { + int ld_moved, cur_ld_moved, active_balance = 0; +- struct sched_domain *sd_parent = sd->parent; ++ struct sched_domain *sd_parent = lb_sd_parent(sd) ? sd->parent : NULL; + struct sched_group *group; + struct rq *busiest; + unsigned long flags; +-- +1.9.1 + |