From 80b15c7389caa81a3860f9fc2ee47ec0ea572a63 Mon Sep 17 00:00:00 2001 From: Konstantin Khlebnikov Date: Thu, 20 May 2010 23:21:41 +0400 Subject: cfq-iosched: compact io_context radix_tree Use small consequent indexes as radix tree keys instead of sparse cfqd address. This change will reduce radix tree depth from 11 (6 for 32-bit hosts) to 1 if host have <=64 disks under cfq control, or to 0 if there only one disk. So, this patch save 10*560 bytes for each process (5*296 for 32-bit hosts) For each cfqd allocate cic index from ida. To unlink dead cic from tree without cfqd access store index into ->key. (bit 0 -- dead mark, bits 1..30 -- index: ida produce id in range 0..2^31-1) Signed-off-by: Konstantin Khlebnikov Signed-off-by: Jens Axboe --- block/cfq-iosched.c | 44 +++++++++++++++++++++++++++++++++++++++----- 1 file changed, 39 insertions(+), 5 deletions(-) (limited to 'block') diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 40760235035..c72e5acc573 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -64,6 +64,9 @@ static DEFINE_PER_CPU(unsigned long, cfq_ioc_count); static struct completion *ioc_gone; static DEFINE_SPINLOCK(ioc_gone_lock); +static DEFINE_SPINLOCK(cic_index_lock); +static DEFINE_IDA(cic_index_ida); + #define CFQ_PRIO_LISTS IOPRIO_BE_NR #define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE) #define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT) @@ -271,6 +274,7 @@ struct cfq_data { unsigned int cfq_latency; unsigned int cfq_group_isolation; + unsigned int cic_index; struct list_head cic_list; /* @@ -431,10 +435,11 @@ static inline void cic_set_cfqq(struct cfq_io_context *cic, } #define CIC_DEAD_KEY 1ul +#define CIC_DEAD_INDEX_SHIFT 1 static inline void *cfqd_dead_key(struct cfq_data *cfqd) { - return (void *)((unsigned long) cfqd | CIC_DEAD_KEY); + return (void *)(cfqd->cic_index << CIC_DEAD_INDEX_SHIFT | CIC_DEAD_KEY); } static inline struct cfq_data *cic_to_cfqd(struct cfq_io_context *cic) @@ -2532,7 +2537,7 @@ static void cic_free_func(struct io_context *ioc, struct cfq_io_context *cic) BUG_ON(!(dead_key & CIC_DEAD_KEY)); spin_lock_irqsave(&ioc->lock, flags); - radix_tree_delete(&ioc->radix_root, dead_key & ~CIC_DEAD_KEY); + radix_tree_delete(&ioc->radix_root, dead_key >> CIC_DEAD_INDEX_SHIFT); hlist_del_rcu(&cic->cic_list); spin_unlock_irqrestore(&ioc->lock, flags); @@ -2906,7 +2911,7 @@ cfq_drop_dead_cic(struct cfq_data *cfqd, struct io_context *ioc, BUG_ON(ioc->ioc_data == cic); - radix_tree_delete(&ioc->radix_root, (unsigned long) cfqd); + radix_tree_delete(&ioc->radix_root, cfqd->cic_index); hlist_del_rcu(&cic->cic_list); spin_unlock_irqrestore(&ioc->lock, flags); @@ -2934,7 +2939,7 @@ cfq_cic_lookup(struct cfq_data *cfqd, struct io_context *ioc) } do { - cic = radix_tree_lookup(&ioc->radix_root, (unsigned long) cfqd); + cic = radix_tree_lookup(&ioc->radix_root, cfqd->cic_index); rcu_read_unlock(); if (!cic) break; @@ -2971,7 +2976,7 @@ static int cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc, spin_lock_irqsave(&ioc->lock, flags); ret = radix_tree_insert(&ioc->radix_root, - (unsigned long) cfqd, cic); + cfqd->cic_index, cic); if (!ret) hlist_add_head_rcu(&cic->cic_list, &ioc->cic_list); spin_unlock_irqrestore(&ioc->lock, flags); @@ -3723,10 +3728,32 @@ static void cfq_exit_queue(struct elevator_queue *e) cfq_shutdown_timer_wq(cfqd); + spin_lock(&cic_index_lock); + ida_remove(&cic_index_ida, cfqd->cic_index); + spin_unlock(&cic_index_lock); + /* Wait for cfqg->blkg->key accessors to exit their grace periods. */ call_rcu(&cfqd->rcu, cfq_cfqd_free); } +static int cfq_alloc_cic_index(void) +{ + int index, error; + + do { + if (!ida_pre_get(&cic_index_ida, GFP_KERNEL)) + return -ENOMEM; + + spin_lock(&cic_index_lock); + error = ida_get_new(&cic_index_ida, &index); + spin_unlock(&cic_index_lock); + if (error && error != -EAGAIN) + return error; + } while (error); + + return index; +} + static void *cfq_init_queue(struct request_queue *q) { struct cfq_data *cfqd; @@ -3734,10 +3761,16 @@ static void *cfq_init_queue(struct request_queue *q) struct cfq_group *cfqg; struct cfq_rb_root *st; + i = cfq_alloc_cic_index(); + if (i < 0) + return NULL; + cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node); if (!cfqd) return NULL; + cfqd->cic_index = i; + /* Init root service tree */ cfqd->grp_service_tree = CFQ_RB_ROOT; @@ -3999,6 +4032,7 @@ static void __exit cfq_exit(void) */ if (elv_ioc_count_read(cfq_ioc_count)) wait_for_completion(&all_gone); + ida_destroy(&cic_index_ida); cfq_slab_kill(); } -- cgit v1.2.3