Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932320AbcLOUdx (ORCPT ); Thu, 15 Dec 2016 15:33:53 -0500 Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:47687 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1756407AbcLOUdV (ORCPT ); Thu, 15 Dec 2016 15:33:21 -0500 Smtp-Origin-Hostprefix: devbig From: Shaohua Li Smtp-Origin-Hostname: devbig638.prn2.facebook.com To: , CC: , , , Smtp-Origin-Cluster: prn2c22 Subject: [PATCH V5 06/17] blk-throttle: add downgrade logic Date: Thu, 15 Dec 2016 12:32:57 -0800 Message-ID: <5c22098d912d73388bc214c1d7e404f25cfdad13.1481833017.git.shli@fb.com> X-Mailer: git-send-email 2.9.3 In-Reply-To: References: X-FB-Internal: Safe MIME-Version: 1.0 Content-Type: text/plain X-Proofpoint-Spam-Reason: safe X-FB-Internal: Safe X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2016-12-15_14:,, signatures=0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 7240 Lines: 239 When queue state machine is in LIMIT_MAX state, but a cgroup is below its low limit for some time, the queue should be downgraded to lower state as one cgroup's low limit isn't met. Signed-off-by: Shaohua Li --- block/blk-throttle.c | 148 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 148 insertions(+) diff --git a/block/blk-throttle.c b/block/blk-throttle.c index cfd74cfc..0f65fce 100644 --- a/block/blk-throttle.c +++ b/block/blk-throttle.c @@ -140,6 +140,13 @@ struct throtl_grp { /* Number of bio's dispatched in current slice */ unsigned int io_disp[2]; + unsigned long last_low_overflow_time[2]; + + uint64_t last_bytes_disp[2]; + unsigned int last_io_disp[2]; + + unsigned long last_check_time; + /* When did we start a new slice */ unsigned long slice_start[2]; unsigned long slice_end[2]; @@ -159,6 +166,9 @@ struct throtl_data struct work_struct dispatch_work; unsigned int limit_index; bool limit_valid[LIMIT_CNT]; + + unsigned long low_upgrade_time; + unsigned long low_downgrade_time; }; static void throtl_pending_timer_fn(unsigned long arg); @@ -896,6 +906,8 @@ static void throtl_charge_bio(struct throtl_grp *tg, struct bio *bio) /* Charge the bio to the group */ tg->bytes_disp[rw] += bio->bi_iter.bi_size; tg->io_disp[rw]++; + tg->last_bytes_disp[rw] += bio->bi_iter.bi_size; + tg->last_io_disp[rw]++; /* * BIO_THROTTLED is used to prevent the same bio to be throttled @@ -1511,6 +1523,36 @@ static struct blkcg_policy blkcg_policy_throtl = { .pd_free_fn = throtl_pd_free, }; +static unsigned long __tg_last_low_overflow_time(struct throtl_grp *tg) +{ + unsigned long rtime = -1, wtime = -1; + + if (tg->bps[READ][LIMIT_LOW] != U64_MAX || + tg->iops[READ][LIMIT_LOW] != UINT_MAX) + rtime = tg->last_low_overflow_time[READ]; + if (tg->bps[WRITE][LIMIT_LOW] != U64_MAX || + tg->iops[WRITE][LIMIT_LOW] != UINT_MAX) + wtime = tg->last_low_overflow_time[WRITE]; + return min(rtime, wtime) == -1 ? 0 : min(rtime, wtime); +} + +static unsigned long tg_last_low_overflow_time(struct throtl_grp *tg) +{ + struct throtl_service_queue *parent_sq; + struct throtl_grp *parent = tg; + unsigned long ret = __tg_last_low_overflow_time(tg); + + while (true) { + parent_sq = parent->service_queue.parent_sq; + parent = sq_to_tg(parent_sq); + if (!parent) + break; + if (time_after(__tg_last_low_overflow_time(parent), ret)) + ret = __tg_last_low_overflow_time(parent); + } + return ret; +} + static bool throtl_tg_can_upgrade(struct throtl_grp *tg) { struct throtl_service_queue *sq = &tg->service_queue; @@ -1555,6 +1597,9 @@ static bool throtl_can_upgrade(struct throtl_data *td, if (td->limit_index != LIMIT_LOW) return false; + if (time_before(jiffies, td->low_downgrade_time + throtl_slice)) + 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); @@ -1578,6 +1623,7 @@ static void throtl_upgrade_state(struct throtl_data *td) struct blkcg_gq *blkg; td->limit_index = LIMIT_MAX; + td->low_upgrade_time = jiffies; rcu_read_lock(); blkg_for_each_descendant_post(blkg, pos_css, td->queue->root_blkg) { struct throtl_grp *tg = blkg_to_tg(blkg); @@ -1593,6 +1639,100 @@ static void throtl_upgrade_state(struct throtl_data *td) queue_work(kthrotld_workqueue, &td->dispatch_work); } +static void throtl_downgrade_state(struct throtl_data *td, int new) +{ + td->limit_index = new; + td->low_downgrade_time = jiffies; +} + +static bool throtl_tg_can_downgrade(struct throtl_grp *tg) +{ + struct throtl_data *td = tg->td; + unsigned long now = jiffies; + + /* + * If cgroup is below low limit, consider downgrade and throttle other + * cgroups + */ + if (time_after_eq(now, td->low_upgrade_time + throtl_slice) && + time_after_eq(now, tg_last_low_overflow_time(tg) + throtl_slice)) + return true; + return false; +} + +static bool throtl_hierarchy_can_downgrade(struct throtl_grp *tg) +{ + while (true) { + if (!throtl_tg_can_downgrade(tg)) + return false; + tg = sq_to_tg(tg->service_queue.parent_sq); + if (!tg || (cgroup_subsys_on_dfl(io_cgrp_subsys) && + !tg_to_blkg(tg)->parent)) + break; + } + return true; +} + +static void throtl_downgrade_check(struct throtl_grp *tg) +{ + uint64_t bps; + unsigned int iops; + unsigned long elapsed_time; + unsigned long now = jiffies; + + if (tg->td->limit_index != LIMIT_MAX || + !tg->td->limit_valid[LIMIT_LOW]) + return; + if (!list_empty(&tg_to_blkg(tg)->blkcg->css.children)) + return; + if (time_after(tg->last_check_time + throtl_slice, now)) + return; + + elapsed_time = now - tg->last_check_time; + tg->last_check_time = now; + + if (time_before(now, tg_last_low_overflow_time(tg) + throtl_slice)) + return; + + if (tg->bps[READ][LIMIT_LOW] != U64_MAX) { + bps = tg->last_bytes_disp[READ] * HZ; + do_div(bps, elapsed_time); + if (bps >= tg->bps[READ][LIMIT_LOW]) + tg->last_low_overflow_time[READ] = now; + } + + if (tg->bps[WRITE][LIMIT_LOW] != U64_MAX) { + bps = tg->last_bytes_disp[WRITE] * HZ; + do_div(bps, elapsed_time); + if (bps >= tg->bps[WRITE][LIMIT_LOW]) + tg->last_low_overflow_time[WRITE] = now; + } + + if (tg->iops[READ][LIMIT_LOW] != UINT_MAX) { + iops = tg->last_io_disp[READ] * HZ / elapsed_time; + if (iops >= tg->iops[READ][LIMIT_LOW]) + tg->last_low_overflow_time[READ] = now; + } + + if (tg->iops[WRITE][LIMIT_LOW] != UINT_MAX) { + iops = tg->last_io_disp[WRITE] * HZ / elapsed_time; + if (iops >= tg->iops[WRITE][LIMIT_LOW]) + tg->last_low_overflow_time[WRITE] = now; + } + + /* + * If cgroup is below low limit, consider downgrade and throttle other + * cgroups + */ + if (throtl_hierarchy_can_downgrade(tg)) + throtl_downgrade_state(tg->td, LIMIT_LOW); + + tg->last_bytes_disp[READ] = 0; + tg->last_bytes_disp[WRITE] = 0; + tg->last_io_disp[READ] = 0; + tg->last_io_disp[WRITE] = 0; +} + bool blk_throtl_bio(struct request_queue *q, struct blkcg_gq *blkg, struct bio *bio) { @@ -1617,12 +1757,16 @@ bool blk_throtl_bio(struct request_queue *q, struct blkcg_gq *blkg, again: while (true) { + if (tg->last_low_overflow_time[rw] == 0) + tg->last_low_overflow_time[rw] = jiffies; + throtl_downgrade_check(tg); /* 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)) { + tg->last_low_overflow_time[rw] = jiffies; if (throtl_can_upgrade(tg->td, tg)) { throtl_upgrade_state(tg->td); goto again; @@ -1666,6 +1810,8 @@ bool blk_throtl_bio(struct request_queue *q, struct blkcg_gq *blkg, tg->io_disp[rw], tg_iops_limit(tg, rw), sq->nr_queued[READ], sq->nr_queued[WRITE]); + tg->last_low_overflow_time[rw] = jiffies; + bio_associate_current(bio); tg->td->nr_queued[rw]++; throtl_add_bio_tg(bio, qn, tg); @@ -1776,6 +1922,8 @@ int blk_throtl_init(struct request_queue *q) td->limit_valid[LIMIT_MAX] = true; td->limit_index = LIMIT_MAX; + td->low_upgrade_time = jiffies; + td->low_downgrade_time = jiffies; /* activate policy */ ret = blkcg_activate_policy(q, &blkcg_policy_throtl); if (ret) -- 2.9.3