From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:47682 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1756275AbcLOUdK (ORCPT ); Thu, 15 Dec 2016 15:33:10 -0500 Received: from pps.filterd (m0001255.ppops.net [127.0.0.1]) by mx0b-00082601.pphosted.com (8.16.0.17/8.16.0.17) with SMTP id uBFKVvON023892 for ; Thu, 15 Dec 2016 12:33:10 -0800 Received: from mail.thefacebook.com ([199.201.64.23]) by mx0b-00082601.pphosted.com with ESMTP id 27bdne5btm-1 (version=TLSv1 cipher=ECDHE-RSA-AES256-SHA bits=256 verify=NOT) for ; Thu, 15 Dec 2016 12:33:10 -0800 Received: from facebook.com (2401:db00:21:603d:face:0:19:0) by mx-out.facebook.com (10.102.107.97) with ESMTP id b0bb7cacc30511e682860002c99331b0-87bf4a50 for ; Thu, 15 Dec 2016 12:33:08 -0800 From: Shaohua Li To: , CC: , , , Subject: [PATCH V5 05/17] blk-throttle: add upgrade logic for LIMIT_LOW state Date: Thu, 15 Dec 2016 12:32:56 -0800 Message-ID: <75685643afd126cbccefe894ca56fd5dd83fe8cf.1481833017.git.shli@fb.com> In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain Sender: linux-block-owner@vger.kernel.org List-Id: linux-block@vger.kernel.org When queue is in LIMIT_LOW state and all cgroups with low limit cross the bps/iops limitation, we will upgrade queue's state to LIMIT_MAX For a cgroup hierarchy, there are two cases. Children has lower low limit than parent. Parent's low limit is meaningless. If children's bps/iops cross low limit, we can upgrade queue state. The other case is children has higher low limit than parent. Children's low limit is meaningless. As long as parent's bps/iops cross low limit, we can upgrade queue state. Signed-off-by: Shaohua Li --- block/blk-throttle.c | 101 +++++++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 97 insertions(+), 4 deletions(-) diff --git a/block/blk-throttle.c b/block/blk-throttle.c index e55bd36..cfd74cfc 100644 --- a/block/blk-throttle.c +++ b/block/blk-throttle.c @@ -455,6 +455,7 @@ static void blk_throtl_update_valid_limit(struct throtl_data *td) td->limit_valid[LIMIT_LOW] = false; } +static void throtl_upgrade_state(struct throtl_data *td); static void throtl_pd_offline(struct blkg_policy_data *pd) { struct throtl_grp *tg = pd_to_tg(pd); @@ -466,9 +467,8 @@ static void throtl_pd_offline(struct blkg_policy_data *pd) blk_throtl_update_valid_limit(tg->td); - if (tg->td->limit_index == LIMIT_LOW && - !tg->td->limit_valid[LIMIT_LOW]) - tg->td->limit_index = LIMIT_MAX; + if (!tg->td->limit_valid[tg->td->limit_index]) + throtl_upgrade_state(tg->td); } static void throtl_pd_free(struct blkg_policy_data *pd) @@ -1077,6 +1077,8 @@ static int throtl_select_dispatch(struct throtl_service_queue *parent_sq) return nr_disp; } +static bool throtl_can_upgrade(struct throtl_data *td, + struct throtl_grp *this_tg); /** * throtl_pending_timer_fn - timer function for service_queue->pending_timer * @arg: the throtl_service_queue being serviced @@ -1103,6 +1105,9 @@ static void throtl_pending_timer_fn(unsigned long arg) int ret; spin_lock_irq(q->queue_lock); + if (throtl_can_upgrade(td, NULL)) + throtl_upgrade_state(td); + again: parent_sq = sq->parent_sq; dispatched = false; @@ -1506,6 +1511,88 @@ static struct blkcg_policy blkcg_policy_throtl = { .pd_free_fn = throtl_pd_free, }; +static bool throtl_tg_can_upgrade(struct throtl_grp *tg) +{ + struct throtl_service_queue *sq = &tg->service_queue; + bool read_limit, write_limit; + + /* + * if cgroup reaches low/max limit (max >= low), it's ok to next + * limit + */ + read_limit = tg->bps[READ][LIMIT_LOW] != U64_MAX || + tg->iops[READ][LIMIT_LOW] != UINT_MAX; + write_limit = tg->bps[WRITE][LIMIT_LOW] != U64_MAX || + tg->iops[WRITE][LIMIT_LOW] != UINT_MAX; + if (read_limit && sq->nr_queued[READ] && + (!write_limit || sq->nr_queued[WRITE])) + return true; + if (write_limit && sq->nr_queued[WRITE] && + (!read_limit || sq->nr_queued[READ])) + return true; + return false; +} + +static bool throtl_hierarchy_can_upgrade(struct throtl_grp *tg) +{ + while (true) { + if (throtl_tg_can_upgrade(tg)) + return true; + tg = sq_to_tg(tg->service_queue.parent_sq); + if (!tg || (cgroup_subsys_on_dfl(io_cgrp_subsys) && + !tg_to_blkg(tg)->parent)) + return false; + } + return false; +} + +static bool throtl_can_upgrade(struct throtl_data *td, + struct throtl_grp *this_tg) +{ + struct cgroup_subsys_state *pos_css; + struct blkcg_gq *blkg; + + if (td->limit_index != LIMIT_LOW) + return false; + + rcu_read_lock(); + blkg_for_each_descendant_post(blkg, pos_css, td->queue->root_blkg) { + struct throtl_grp *tg = blkg_to_tg(blkg); + + if (tg == this_tg) + continue; + if (!list_empty(&tg_to_blkg(tg)->blkcg->css.children)) + continue; + if (!throtl_hierarchy_can_upgrade(tg)) { + rcu_read_unlock(); + return false; + } + } + rcu_read_unlock(); + return true; +} + +static void throtl_upgrade_state(struct throtl_data *td) +{ + struct cgroup_subsys_state *pos_css; + struct blkcg_gq *blkg; + + td->limit_index = LIMIT_MAX; + rcu_read_lock(); + blkg_for_each_descendant_post(blkg, pos_css, td->queue->root_blkg) { + struct throtl_grp *tg = blkg_to_tg(blkg); + struct throtl_service_queue *sq = &tg->service_queue; + + tg->disptime = jiffies - 1; + throtl_select_dispatch(sq); + throtl_schedule_next_dispatch(sq, false); + } + rcu_read_unlock(); + throtl_select_dispatch(&td->service_queue); + throtl_schedule_next_dispatch(&td->service_queue, false); + queue_work(kthrotld_workqueue, &td->dispatch_work); +} + bool blk_throtl_bio(struct request_queue *q, struct blkcg_gq *blkg, struct bio *bio) { @@ -1528,14 +1615,20 @@ bool blk_throtl_bio(struct request_queue *q, struct blkcg_gq *blkg, sq = &tg->service_queue; +again: while (true) { /* throtl is FIFO - if bios are already queued, should queue */ if (sq->nr_queued[rw]) break; /* if above limits, break to queue */ - if (!tg_may_dispatch(tg, bio, NULL)) + if (!tg_may_dispatch(tg, bio, NULL)) { + if (throtl_can_upgrade(tg->td, tg)) { + throtl_upgrade_state(tg->td); + goto again; + } break; + } /* within limits, let's charge and dispatch directly */ throtl_charge_bio(tg, bio); -- 2.9.3