This commit moves the ->reschedule_jiffies, ->reschedule_count, and ->work fields from the srcu_struct structure to the srcu_usage structure to reduce the size of the former in order to improve cache locality. However, this means that the container_of() calls cannot get a pointer to the srcu_struct because they are no longer in the srcu_struct. This issue is addressed by adding a ->srcu_ssp field in the srcu_usage structure that references the corresponding srcu_struct structure. And given the presence of the sup pointer to the srcu_usage structure, replace some ssp->srcu_usage-> instances with sup->. [ paulmck Apply feedback from kernel test robot. ] Link: https://lore.kernel.org/oe-kbuild-all/202303191400.iO5BOqka-lkp@xxxxxxxxx/ Suggested-by: Christoph Hellwig <hch@xxxxxx> Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx> --- include/linux/srcutree.h | 9 +++++---- kernel/rcu/srcutree.c | 41 +++++++++++++++++++++------------------- 2 files changed, 27 insertions(+), 23 deletions(-) diff --git a/include/linux/srcutree.h b/include/linux/srcutree.h index 70f5a3abe80a..8f3f72480e78 100644 --- a/include/linux/srcutree.h +++ b/include/linux/srcutree.h @@ -84,6 +84,10 @@ struct srcu_usage { atomic_t srcu_barrier_cpu_cnt; /* # CPUs not yet posting a */ /* callback for the barrier */ /* operation. */ + unsigned long reschedule_jiffies; + unsigned long reschedule_count; + struct delayed_work work; + struct srcu_struct *srcu_ssp; }; /* @@ -92,9 +96,6 @@ struct srcu_usage { struct srcu_struct { unsigned int srcu_idx; /* Current rdr array element. */ struct srcu_data __percpu *sda; /* Per-CPU srcu_data array. */ - unsigned long reschedule_jiffies; - unsigned long reschedule_count; - struct delayed_work work; struct lockdep_map dep_map; struct srcu_usage *srcu_sup; /* Update-side data. */ }; @@ -132,10 +133,10 @@ struct srcu_struct { { \ .lock = __SPIN_LOCK_UNLOCKED(name.lock), \ .srcu_gp_seq_needed = -1UL, \ + .work = __DELAYED_WORK_INITIALIZER(name.work, NULL, 0), \ } #define __SRCU_STRUCT_INIT_COMMON(name, usage_name) \ - .work = __DELAYED_WORK_INITIALIZER(name.work, NULL, 0), \ .srcu_sup = &usage_name, \ __SRCU_DEP_MAP_INIT(name) diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c index 1df4a1467765..22dc266d2090 100644 --- a/kernel/rcu/srcutree.c +++ b/kernel/rcu/srcutree.c @@ -251,7 +251,7 @@ static int init_srcu_struct_fields(struct srcu_struct *ssp, bool is_static) ssp->srcu_sup->srcu_barrier_seq = 0; mutex_init(&ssp->srcu_sup->srcu_barrier_mutex); atomic_set(&ssp->srcu_sup->srcu_barrier_cpu_cnt, 0); - INIT_DELAYED_WORK(&ssp->work, process_srcu); + INIT_DELAYED_WORK(&ssp->srcu_sup->work, process_srcu); ssp->srcu_sup->sda_is_static = is_static; if (!is_static) ssp->sda = alloc_percpu(struct srcu_data); @@ -275,6 +275,7 @@ static int init_srcu_struct_fields(struct srcu_struct *ssp, bool is_static) WRITE_ONCE(ssp->srcu_sup->srcu_size_state, SRCU_SIZE_BIG); } } + ssp->srcu_sup->srcu_ssp = ssp; smp_store_release(&ssp->srcu_sup->srcu_gp_seq_needed, 0); /* Init done. */ return 0; } @@ -647,7 +648,7 @@ void cleanup_srcu_struct(struct srcu_struct *ssp) return; /* Just leak it! */ if (WARN_ON(srcu_readers_active(ssp))) return; /* Just leak it! */ - flush_delayed_work(&ssp->work); + flush_delayed_work(&ssp->srcu_sup->work); for_each_possible_cpu(cpu) { struct srcu_data *sdp = per_cpu_ptr(ssp->sda, cpu); @@ -1059,10 +1060,10 @@ static void srcu_funnel_gp_start(struct srcu_struct *ssp, struct srcu_data *sdp, // can only be executed during early boot when there is only // the one boot CPU running with interrupts still disabled. if (likely(srcu_init_done)) - queue_delayed_work(rcu_gp_wq, &ssp->work, + queue_delayed_work(rcu_gp_wq, &ssp->srcu_sup->work, !!srcu_get_delay(ssp)); - else if (list_empty(&ssp->work.work.entry)) - list_add(&ssp->work.work.entry, &srcu_boot_list); + else if (list_empty(&ssp->srcu_sup->work.work.entry)) + list_add(&ssp->srcu_sup->work.work.entry, &srcu_boot_list); } spin_unlock_irqrestore_rcu_node(ssp->srcu_sup, flags); } @@ -1745,7 +1746,7 @@ static void srcu_reschedule(struct srcu_struct *ssp, unsigned long delay) spin_unlock_irq_rcu_node(ssp->srcu_sup); if (pushgp) - queue_delayed_work(rcu_gp_wq, &ssp->work, delay); + queue_delayed_work(rcu_gp_wq, &ssp->srcu_sup->work, delay); } /* @@ -1756,22 +1757,24 @@ static void process_srcu(struct work_struct *work) unsigned long curdelay; unsigned long j; struct srcu_struct *ssp; + struct srcu_usage *sup; - ssp = container_of(work, struct srcu_struct, work.work); + sup = container_of(work, struct srcu_usage, work.work); + ssp = sup->srcu_ssp; srcu_advance_state(ssp); curdelay = srcu_get_delay(ssp); if (curdelay) { - WRITE_ONCE(ssp->reschedule_count, 0); + WRITE_ONCE(sup->reschedule_count, 0); } else { j = jiffies; - if (READ_ONCE(ssp->reschedule_jiffies) == j) { - WRITE_ONCE(ssp->reschedule_count, READ_ONCE(ssp->reschedule_count) + 1); - if (READ_ONCE(ssp->reschedule_count) > srcu_max_nodelay) + if (READ_ONCE(sup->reschedule_jiffies) == j) { + WRITE_ONCE(sup->reschedule_count, READ_ONCE(sup->reschedule_count) + 1); + if (READ_ONCE(sup->reschedule_count) > srcu_max_nodelay) curdelay = 1; } else { - WRITE_ONCE(ssp->reschedule_count, 1); - WRITE_ONCE(ssp->reschedule_jiffies, j); + WRITE_ONCE(sup->reschedule_count, 1); + WRITE_ONCE(sup->reschedule_jiffies, j); } } srcu_reschedule(ssp, curdelay); @@ -1870,7 +1873,7 @@ early_initcall(srcu_bootup_announce); void __init srcu_init(void) { - struct srcu_struct *ssp; + struct srcu_usage *sup; /* Decide on srcu_struct-size strategy. */ if (SRCU_SIZING_IS(SRCU_SIZING_AUTO)) { @@ -1890,13 +1893,13 @@ void __init srcu_init(void) */ srcu_init_done = true; while (!list_empty(&srcu_boot_list)) { - ssp = list_first_entry(&srcu_boot_list, struct srcu_struct, + sup = list_first_entry(&srcu_boot_list, struct srcu_usage, work.work.entry); - list_del_init(&ssp->work.work.entry); + list_del_init(&sup->work.work.entry); if (SRCU_SIZING_IS(SRCU_SIZING_INIT) && - ssp->srcu_sup->srcu_size_state == SRCU_SIZE_SMALL) - ssp->srcu_sup->srcu_size_state = SRCU_SIZE_ALLOC; - queue_work(rcu_gp_wq, &ssp->work.work); + sup->srcu_size_state == SRCU_SIZE_SMALL) + sup->srcu_size_state = SRCU_SIZE_ALLOC; + queue_work(rcu_gp_wq, &sup->work.work); } } -- 2.40.0.rc2
