Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756572Ab0LMBo0 (ORCPT ); Sun, 12 Dec 2010 20:44:26 -0500 Received: from cn.fujitsu.com ([222.73.24.84]:49265 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1754346Ab0LMBoW (ORCPT ); Sun, 12 Dec 2010 20:44:22 -0500 Message-ID: <4D057A8D.1020704@cn.fujitsu.com> Date: Mon, 13 Dec 2010 09:44:45 +0800 From: Gui Jianfeng User-Agent: Thunderbird 2.0.0.24 (Windows/20100228) MIME-Version: 1.0 To: Jens Axboe , Vivek Goyal CC: Gui Jianfeng , Corrado Zoccolo , Chad Talbott , Nauman Rafique , Divyesh Shah , linux kernel mailing list Subject: [PATCH 3/8 v2] cfq-iosched: Introduce vdisktime and io weight for CFQ queue References: <4CDF7BC5.9080803@cn.fujitsu.com> <4CDF9CC6.2040106@cn.fujitsu.com> <20101115165319.GI30792@redhat.com> <4CE2718C.6010406@kernel.dk> <4D01C6AB.9040807@cn.fujitsu.com> In-Reply-To: <4D01C6AB.9040807@cn.fujitsu.com> X-MIMETrack: Itemize by SMTP Server on mailserver/fnst(Release 8.5.1FP4|July 25, 2010) at 2010-12-13 09:44:21, Serialize by Router on mailserver/fnst(Release 8.5.1FP4|July 25, 2010) at 2010-12-13 09:44:21, Serialize complete at 2010-12-13 09:44:21 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 Content-Length: 12066 Lines: 389 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. But it still give newly added cfqq a small vdisktime jump according to its ioprio. This patch will help to make CFQ queue and group schedule on a same service tree. Signed-off-by: Gui Jianfeng --- block/cfq-iosched.c | 196 ++++++++++++++++++++++++++++++++++++--------------- 1 files changed, 139 insertions(+), 57 deletions(-) diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 91e9833..30d19c0 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -101,10 +101,7 @@ struct cfq_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 is_group_entity; unsigned int weight; @@ -116,6 +113,8 @@ struct cfq_entity { struct cfq_queue { /* The schedule entity */ struct cfq_entity cfqe; + /* Reposition time */ + unsigned long reposition_time; /* reference count */ atomic_t ref; /* various state flags, see below */ @@ -314,6 +313,22 @@ 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 cfq_entity *cfqe) { @@ -841,16 +856,6 @@ 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 cfq_entity *entity) { @@ -1199,6 +1204,16 @@ static inline void cfq_put_cfqg(struct cfq_group *cfqg) {} #endif /* GROUP_IOSCHED */ +static inline u64 cfq_get_boost(struct cfq_data *cfqd, + struct cfq_entity *cfqe) +{ + u64 d = cfqd->cfq_slice[1] << CFQ_SERVICE_SHIFT; + + d = d * BLKIO_WEIGHT_DEFAULT; + do_div(d, BLKIO_WEIGHT_MAX - cfqe->weight + BLKIO_WEIGHT_MIN); + return d; +} + /* * The cfqd->service_trees holds all pending cfq_queue's that have * requests waiting to be processed. It is sorted in the order that @@ -1210,13 +1225,14 @@ static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq, struct cfq_entity *cfqe; struct rb_node **p, *parent; struct cfq_entity *__cfqe; - 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; cfqe = &cfqq->cfqe; + orig_st = cfqe->service_tree; #ifdef CONFIG_CFQ_GROUP_IOSCHED if (!cfqd->cfq_group_isolation @@ -1224,8 +1240,15 @@ 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(&cfqe->rb_node)) + if (!RB_EMPTY_NODE(&cfqe->rb_node)) { cfq_group_service_tree_del(cfqd, cfqq->cfqg); + /* + * Group changed, dequeue this CFQ queue from the + * original service tree. + */ + cfq_rb_erase(&cfqe->rb_node, cfqe->service_tree); + orig_st->total_weight -= cfqe->weight; + } cfqq->orig_cfqg = cfqq->cfqg; cfqq->cfqg = &cfqd->root_group; atomic_inc(&cfqd->root_group.ref); @@ -1234,8 +1257,15 @@ 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(&cfqe->rb_node)) + if (!RB_EMPTY_NODE(&cfqe->rb_node)) { cfq_group_service_tree_del(cfqd, cfqq->cfqg); + /* + * Group changed, dequeue this CFQ queue from the + * original service tree. + */ + cfq_rb_erase(&cfqe->rb_node, cfqe->service_tree); + orig_st->total_weight -= cfqe->weight; + } cfq_put_cfqg(cfqq->cfqg); cfqq->cfqg = cfqq->orig_cfqg; cfqq->orig_cfqg = NULL; @@ -1246,50 +1276,73 @@ 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(&cfqe->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) { + u64 boost; + s64 __vdisktime; + + __cfqe = rb_entry_entity(parent); + cfqe->vdisktime = __cfqe->vdisktime + CFQ_IDLE_DELAY; + + /* Give some vdisktime boost according to its weight */ + boost = cfq_get_boost(cfqd, cfqe); + __vdisktime = cfqe->vdisktime - boost; + if (__vdisktime) + cfqe->vdisktime = __vdisktime; + else + cfqe->vdisktime = 0; + } else + cfqe->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(&cfqe->rb_node, cfqe->service_tree); + orig_st->total_weight -= cfqe->weight; + + new_cfqq = 0; + if (cfq_class_idle(cfqq)) { - rb_key = CFQ_IDLE_DELAY; parent = rb_last(&service_tree->rb); if (parent && parent != &cfqe->rb_node) { __cfqe = rb_entry(parent, - struct cfq_entity, - rb_node); - rb_key += __cfqe->rb_key; + struct cfq_entity, + rb_node); + cfqe->vdisktime = __cfqe->vdisktime + CFQ_IDLE_DELAY; } else - rb_key += jiffies; + cfqe->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. + * We charge the CFQ queue by the time this queue runs, and + * repsition it on the service tree. */ - rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies; - rb_key -= cfqq->slice_resid; - cfqq->slice_resid = 0; - } else { - rb_key = -HZ; - __cfqe = cfq_rb_first(service_tree); - rb_key += __cfqe ? __cfqe->rb_key : jiffies; - } + unsigned int used_sl; - if (!RB_EMPTY_NODE(&cfqe->rb_node)) { - new_cfqq = 0; - /* - * same position, nothing more to do - */ - if (rb_key == cfqe->rb_key && - cfqe->service_tree == service_tree) - return; - - cfq_rb_erase(&cfqe->rb_node, - cfqe->service_tree); - cfqe->service_tree = NULL; + used_sl = cfq_cfqq_slice_usage(cfqq); + cfqe->vdisktime += cfq_scale_slice(used_sl, cfqe); + } else { + cfqe->vdisktime = service_tree->min_vdisktime; } +insert: left = 1; parent = NULL; cfqe->service_tree = service_tree; p = &service_tree->rb.rb_node; + key = entity_key(service_tree, cfqe); while (*p) { struct rb_node **n; @@ -1300,7 +1353,7 @@ 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, __cfqe->rb_key)) + if (key < entity_key(service_tree, __cfqe)) n = &(*p)->rb_left; else { n = &(*p)->rb_right; @@ -1313,10 +1366,12 @@ static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq, if (left) service_tree->left = &cfqe->rb_node; - cfqe->rb_key = rb_key; rb_link_node(&cfqe->rb_node, parent, p); rb_insert_color(&cfqe->rb_node, &service_tree->rb); + update_min_vdisktime(service_tree); service_tree->count++; + service_tree->total_weight += cfqe->weight; + cfqq->reposition_time = jiffies; if ((add_front || !new_cfqq) && !group_changed) return; cfq_group_service_tree_add(cfqd, cfqq->cfqg); @@ -1418,15 +1473,19 @@ 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 cfq_entity *cfqe; + 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); cfqe = &cfqq->cfqe; + service_tree = cfqe->service_tree; if (!RB_EMPTY_NODE(&cfqe->rb_node)) { cfq_rb_erase(&cfqe->rb_node, cfqe->service_tree); + service_tree->total_weight -= cfqe->weight; cfqe->service_tree = NULL; } if (cfqq->p_root) { @@ -2125,24 +2184,34 @@ 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 cfq_entity *cfqe; + 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 */ cfqe = cfq_rb_first(service_tree_for(cfqg, prio, i)); - if (cfqe && - (!key_valid || - time_before(cfqe->rb_key, lowest_key))) { - lowest_key = cfqe->rb_key; + cfqq = cfqq_of_entity(cfqe); + if (cfqe && (!time_valid || + cfqq->reposition_time < lowest_start_time)) { + lowest_start_time = cfqq->reposition_time; cur_best = i; - key_valid = true; + time_valid = true; } } @@ -2814,10 +2883,13 @@ static void cfq_init_prio_data(struct cfq_queue *cfqq, struct io_context *ioc) { struct task_struct *tsk = current; int ioprio_class; + struct cfq_entity *cfqe; if (!cfq_cfqq_prio_changed(cfqq)) return; + cfqe = &cfqq->cfqe; + ioprio_class = IOPRIO_PRIO_CLASS(ioc->ioprio); switch (ioprio_class) { default: @@ -2844,6 +2916,8 @@ static void cfq_init_prio_data(struct cfq_queue *cfqq, struct io_context *ioc) break; } + cfqe->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 @@ -3578,6 +3652,9 @@ static void cfq_completed_request(struct request_queue *q, struct request *rq) */ static void cfq_prio_boost(struct cfq_queue *cfqq) { + struct cfq_entity *cfqe; + + cfqe = &cfqq->cfqe; if (has_fs_excl()) { /* * boost idle prio on transactions that would lock out other @@ -3594,6 +3671,11 @@ 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. + */ + cfqe->weight = cfq_prio_to_weight(cfqq->ioprio); } static inline int __cfq_may_queue(struct cfq_queue *cfqq) -- 1.6.5.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/