From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757243Ab0KOAyD (ORCPT ); Sun, 14 Nov 2010 19:54:03 -0500 Received: from cn.fujitsu.com ([222.73.24.84]:50009 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1755188Ab0KOAyB (ORCPT ); Sun, 14 Nov 2010 19:54:01 -0500 Message-ID: <4CE084A2.7010701@cn.fujitsu.com> Date: Mon, 15 Nov 2010 08:53:54 +0800 From: Gui Jianfeng User-Agent: Thunderbird 2.0.0.24 (Windows/20100228) MIME-Version: 1.0 To: Vivek Goyal , Jens Axboe CC: Corrado Zoccolo , Chad Talbott , Nauman Rafique , Divyesh Shah , linux kernel mailing list , Gui Jianfeng Subject: [RFC] [PATCH 3/8] cfq-iosched: Introduce vdisktime and io weight for CFQ queue X-MIMETrack: Itemize by SMTP Server on mailserver/fnst(Release 8.5.1FP4|July 25, 2010) at 2010-11-15 08:54:23, Serialize by Router on mailserver/fnst(Release 8.5.1FP4|July 25, 2010) at 2010-11-15 08:54:24, Serialize complete at 2010-11-15 08:54:24 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Introduce vdisktime and io weight for CFQ queue scheduling. Currently, io priority maps to a range [100,1000]. It also gets rid of cfq_slice_offset() logic and makes use the same scheduling algorithm as CFQ group does. This helps for CFQ queue and group scheduling on the same service tree. Signed-off-by: Gui Jianfeng --- block/cfq-iosched.c | 194 ++++++++++++++++++++++++++++++++++---------------- 1 files changed, 132 insertions(+), 62 deletions(-) diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 5cce1e8..ef88931 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -102,10 +102,7 @@ struct io_sched_entity { struct cfq_rb_root *service_tree; /* service_tree member */ struct rb_node rb_node; - /* service_tree key, represent the position on the tree */ - unsigned long rb_key; - - /* group service_tree key */ + /* service_tree key */ u64 vdisktime; bool on_st; bool is_group_entity; @@ -118,6 +115,8 @@ struct io_sched_entity { struct cfq_queue { /* The schedule entity */ struct io_sched_entity queue_entity; + /* Reposition time */ + unsigned long reposition_time; /* reference count */ atomic_t ref; /* various state flags, see below */ @@ -306,6 +305,22 @@ struct cfq_data { struct rcu_head rcu; }; +/* + * Map io priority(7 ~ 0) to io weight(100 ~ 1000) + */ +static inline unsigned int cfq_prio_to_weight(unsigned short ioprio) +{ + unsigned int step; + + BUG_ON(ioprio >= IOPRIO_BE_NR); + + step = (BLKIO_WEIGHT_MAX - BLKIO_WEIGHT_MIN) / (IOPRIO_BE_NR - 1); + if (ioprio == 0) + return BLKIO_WEIGHT_MAX; + + return BLKIO_WEIGHT_MIN + (IOPRIO_BE_NR - ioprio - 1) * step; +} + static inline struct cfq_queue * cfqq_of_entity(struct io_sched_entity *io_entity) { @@ -551,12 +566,13 @@ cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio); } -static inline u64 cfq_scale_slice(unsigned long delta, struct cfq_group *cfqg) +static inline u64 +cfq_scale_slice(unsigned long delta, struct io_sched_entity *entity) { u64 d = delta << CFQ_SERVICE_SHIFT; d = d * BLKIO_WEIGHT_DEFAULT; - do_div(d, cfqg->group_entity.weight); + do_div(d, entity->weight); return d; } @@ -581,16 +597,16 @@ static inline u64 min_vdisktime(u64 min_vdisktime, u64 vdisktime) static void update_min_vdisktime(struct cfq_rb_root *st) { u64 vdisktime = st->min_vdisktime; - struct io_sched_entity *group_entity; + struct io_sched_entity *entity; if (st->active) { - group_entity = rb_entry_entity(st->active); - vdisktime = group_entity->vdisktime; + entity = rb_entry_entity(st->active); + vdisktime = entity->vdisktime; } if (st->left) { - group_entity = rb_entry_entity(st->left); - vdisktime = min_vdisktime(vdisktime, group_entity->vdisktime); + entity = rb_entry_entity(st->left); + vdisktime = min_vdisktime(vdisktime, entity->vdisktime); } st->min_vdisktime = max_vdisktime(st->min_vdisktime, vdisktime); @@ -838,16 +854,6 @@ cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq, return cfq_choose_req(cfqd, next, prev, blk_rq_pos(last)); } -static unsigned long cfq_slice_offset(struct cfq_data *cfqd, - struct cfq_queue *cfqq) -{ - /* - * just an approximation, should be ok. - */ - return (cfqq->cfqg->nr_cfqq - 1) * (cfq_prio_slice(cfqd, 1, 0) - - cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio)); -} - static inline s64 entity_key(struct cfq_rb_root *st, struct io_sched_entity *entity) { @@ -983,7 +989,7 @@ static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg, /* Can't update vdisktime while group is on service tree */ cfq_rb_erase(&group_entity->rb_node, st); - group_entity->vdisktime += cfq_scale_slice(charge, cfqg); + group_entity->vdisktime += cfq_scale_slice(charge, group_entity); __cfq_group_service_tree_add(st, cfqg); /* This group is being expired. Save the context */ @@ -1214,13 +1220,14 @@ static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq, struct io_sched_entity *queue_entity; struct rb_node **p, *parent; struct io_sched_entity *__queue_entity; - unsigned long rb_key; - struct cfq_rb_root *service_tree; + struct cfq_rb_root *service_tree, *orig_st; int left; int new_cfqq = 1; int group_changed = 0; + s64 key; queue_entity = &cfqq->queue_entity; + orig_st = queue_entity->service_tree; #ifdef CONFIG_CFQ_GROUP_IOSCHED if (!cfqd->cfq_group_isolation @@ -1228,8 +1235,16 @@ static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq, && cfqq->cfqg && cfqq->cfqg != &cfqd->root_group) { /* Move this cfq to root group */ cfq_log_cfqq(cfqd, cfqq, "moving to root group"); - if (!RB_EMPTY_NODE(&queue_entity->rb_node)) + if (!RB_EMPTY_NODE(&queue_entity->rb_node)) { cfq_group_service_tree_del(cfqd, cfqq->cfqg); + /* + * Group changed, dequeue this CFQ queue from the + * original service tree. + */ + cfq_rb_erase(&queue_entity->rb_node, + queue_entity->service_tree); + orig_st->total_weight -= queue_entity->weight; + } cfqq->orig_cfqg = cfqq->cfqg; cfqq->cfqg = &cfqd->root_group; atomic_inc(&cfqd->root_group.ref); @@ -1238,8 +1253,16 @@ static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq, && cfqq_type(cfqq) == SYNC_WORKLOAD && cfqq->orig_cfqg) { /* cfqq is sequential now needs to go to its original group */ BUG_ON(cfqq->cfqg != &cfqd->root_group); - if (!RB_EMPTY_NODE(&queue_entity->rb_node)) + if (!RB_EMPTY_NODE(&queue_entity->rb_node)) { cfq_group_service_tree_del(cfqd, cfqq->cfqg); + /* + * Group changed, dequeue this CFQ queue from the + * original service tree. + */ + cfq_rb_erase(&queue_entity->rb_node, + queue_entity->service_tree); + orig_st->total_weight -= queue_entity->weight; + } cfq_put_cfqg(cfqq->cfqg); cfqq->cfqg = cfqq->orig_cfqg; cfqq->orig_cfqg = NULL; @@ -1250,50 +1273,67 @@ static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq, service_tree = service_tree_for(cfqq->cfqg, cfqq_prio(cfqq), cfqq_type(cfqq)); + + /* + * For the time being, put the newly added CFQ queue at the end of the + * service tree. + */ + if (RB_EMPTY_NODE(&queue_entity->rb_node)) { + /* + * If this CFQ queue moves to another group, the original + * vdisktime makes no sense any more, reset the vdisktime + * here. + */ + parent = rb_last(&service_tree->rb); + if (parent) { + __queue_entity = rb_entry_entity(parent); + queue_entity->vdisktime = __queue_entity->vdisktime + + CFQ_IDLE_DELAY; + } else + queue_entity->vdisktime = service_tree->min_vdisktime; + + goto insert; + } + + /* + * Ok, we get here, this CFQ queue is on the service tree, dequeue it + * firstly. + */ + cfq_rb_erase(&queue_entity->rb_node, + queue_entity->service_tree); + orig_st->total_weight -= queue_entity->weight; + + new_cfqq = 0; if (cfq_class_idle(cfqq)) { - rb_key = CFQ_IDLE_DELAY; parent = rb_last(&service_tree->rb); if (parent && parent != &queue_entity->rb_node) { __queue_entity = rb_entry(parent, struct io_sched_entity, rb_node); - rb_key += __queue_entity->rb_key; + queue_entity->vdisktime = __queue_entity->vdisktime + + CFQ_IDLE_DELAY; } else - rb_key += jiffies; + queue_entity->vdisktime = service_tree->min_vdisktime; } else if (!add_front) { /* - * Get our rb key offset. Subtract any residual slice - * value carried from last service. A negative resid - * count indicates slice overrun, and this should position - * the next service time further away in the tree. - */ - rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies; - rb_key -= cfqq->slice_resid; - cfqq->slice_resid = 0; - } else { - rb_key = -HZ; - __queue_entity = cfq_rb_first(service_tree); - rb_key += __queue_entity ? __queue_entity->rb_key : jiffies; - } - - if (!RB_EMPTY_NODE(&queue_entity->rb_node)) { - new_cfqq = 0; - /* - * same position, nothing more to do + * We charge the CFQ queue by the time this queue runs, and + * repsition it on the service tree. */ - if (rb_key == queue_entity->rb_key && - queue_entity->service_tree == service_tree) - return; + unsigned int used_sl; - cfq_rb_erase(&queue_entity->rb_node, - queue_entity->service_tree); - queue_entity->service_tree = NULL; + used_sl = cfq_cfqq_slice_usage(cfqq); + queue_entity->vdisktime += cfq_scale_slice(used_sl, + queue_entity); + } else { + queue_entity->vdisktime = service_tree->min_vdisktime; } +insert: left = 1; parent = NULL; queue_entity->service_tree = service_tree; p = &service_tree->rb.rb_node; + key = entity_key(service_tree, queue_entity); while (*p) { struct rb_node **n; @@ -1304,7 +1344,7 @@ static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq, /* * sort by key, that represents service time. */ - if (time_before(rb_key, __queue_entity->rb_key)) + if (key < entity_key(service_tree, __queue_entity)) n = &(*p)->rb_left; else { n = &(*p)->rb_right; @@ -1317,10 +1357,12 @@ static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq, if (left) service_tree->left = &queue_entity->rb_node; - queue_entity->rb_key = rb_key; rb_link_node(&queue_entity->rb_node, parent, p); rb_insert_color(&queue_entity->rb_node, &service_tree->rb); + update_min_vdisktime(service_tree); service_tree->count++; + service_tree->total_weight += queue_entity->weight; + cfqq->reposition_time = jiffies; if ((add_front || !new_cfqq) && !group_changed) return; cfq_group_service_tree_add(cfqd, cfqq->cfqg); @@ -1422,15 +1464,19 @@ static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) { struct io_sched_entity *queue_entity; + struct cfq_rb_root *service_tree; + cfq_log_cfqq(cfqd, cfqq, "del_from_rr"); BUG_ON(!cfq_cfqq_on_rr(cfqq)); cfq_clear_cfqq_on_rr(cfqq); queue_entity = &cfqq->queue_entity; + service_tree = queue_entity->service_tree; if (!RB_EMPTY_NODE(&queue_entity->rb_node)) { cfq_rb_erase(&queue_entity->rb_node, queue_entity->service_tree); + service_tree->total_weight -= queue_entity->weight; queue_entity->service_tree = NULL; } if (cfqq->p_root) { @@ -2132,24 +2178,35 @@ static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq) } } +/* + * The time when a CFQ queue is put onto a service tree is recoreded in + * cfqq->reposition_time. Currently, we check the first priority CFQ queues + * on each service tree, and select the workload type that contain the lowest + * reposition_time CFQ queue among them. + */ static enum wl_type_t cfq_choose_wl(struct cfq_data *cfqd, struct cfq_group *cfqg, enum wl_prio_t prio) { struct io_sched_entity *queue_entity; + struct cfq_queue *cfqq; + unsigned long lowest_start_time; int i; - bool key_valid = false; - unsigned long lowest_key = 0; + bool time_valid = false; enum wl_type_t cur_best = SYNC_NOIDLE_WORKLOAD; + /* + * TODO: We may take io priority into account when choosing a workload + * type. But for the time being just make use of reposition_time only. + */ for (i = 0; i <= SYNC_WORKLOAD; ++i) { - /* select the one with lowest rb_key */ queue_entity = cfq_rb_first(service_tree_for(cfqg, prio, i)); + cfqq = cfqq_of_entity(queue_entity); if (queue_entity && - (!key_valid || - time_before(queue_entity->rb_key, lowest_key))) { - lowest_key = queue_entity->rb_key; + (!time_valid || + cfqq->reposition_time < lowest_start_time)) { + lowest_start_time = cfqq->reposition_time; cur_best = i; - key_valid = true; + time_valid = true; } } @@ -2811,10 +2868,13 @@ static void cfq_init_prio_data(struct cfq_queue *cfqq, struct io_context *ioc) { struct task_struct *tsk = current; int ioprio_class; + struct io_sched_entity *queue_entity; if (!cfq_cfqq_prio_changed(cfqq)) return; + queue_entity = &cfqq->queue_entity; + ioprio_class = IOPRIO_PRIO_CLASS(ioc->ioprio); switch (ioprio_class) { default: @@ -2841,6 +2901,8 @@ static void cfq_init_prio_data(struct cfq_queue *cfqq, struct io_context *ioc) break; } + queue_entity->weight = cfq_prio_to_weight(cfqq->ioprio); + /* * keep track of original prio settings in case we have to temporarily * elevate the priority of this queue @@ -3571,6 +3633,9 @@ static void cfq_completed_request(struct request_queue *q, struct request *rq) */ static void cfq_prio_boost(struct cfq_queue *cfqq) { + struct io_sched_entity *queue_entity; + + queue_entity = &cfqq->queue_entity; if (has_fs_excl()) { /* * boost idle prio on transactions that would lock out other @@ -3587,6 +3652,11 @@ static void cfq_prio_boost(struct cfq_queue *cfqq) cfqq->ioprio_class = cfqq->org_ioprio_class; cfqq->ioprio = cfqq->org_ioprio; } + + /* + * update the io weight if io priority gets changed. + */ + queue_entity->weight = cfq_prio_to_weight(cfqq->ioprio); } static inline int __cfq_may_queue(struct cfq_queue *cfqq) -- 1.6.5.2 -- Regards Gui Jianfeng