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From: Tejun Heo <tj@kernel.org>
To: axboe@kernel.dk
Cc: linux-block@vger.kernel.org, cgroups@vger.kernel.org,
	linux-kernel@vger.kernel.org, kernel-team@fb.com, newella@fb.com,
	Tejun Heo <tj@kernel.org>
Subject: [PATCH 09/27] blk-iocost: use WEIGHT_ONE based fixed point number for weights
Date: Tue,  1 Sep 2020 14:52:39 -0400	[thread overview]
Message-ID: <20200901185257.645114-10-tj@kernel.org> (raw)
In-Reply-To: <20200901185257.645114-1-tj@kernel.org>

To improve weight donations, we want to able to scale inuse with a greater
accuracy and down below 1. Let's make non-hierarchical weights to use
WEIGHT_ONE based fixed point numbers too like hierarchical ones.

This doesn't cause any behavior changes yet.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 block/blk-iocost.c | 25 +++++++++++++------------
 1 file changed, 13 insertions(+), 12 deletions(-)

diff --git a/block/blk-iocost.c b/block/blk-iocost.c
index 5e6d56eec1c9..00c5a3ad2b5b 100644
--- a/block/blk-iocost.c
+++ b/block/blk-iocost.c
@@ -984,8 +984,8 @@ static void current_hweight(struct ioc_gq *iocg, u32 *hw_activep, u32 *hw_inusep
 	for (lvl = 0; lvl <= iocg->level - 1; lvl++) {
 		struct ioc_gq *parent = iocg->ancestors[lvl];
 		struct ioc_gq *child = iocg->ancestors[lvl + 1];
-		u32 active_sum = READ_ONCE(parent->child_active_sum);
-		u32 inuse_sum = READ_ONCE(parent->child_inuse_sum);
+		u64 active_sum = READ_ONCE(parent->child_active_sum);
+		u64 inuse_sum = READ_ONCE(parent->child_inuse_sum);
 		u32 active = READ_ONCE(child->active);
 		u32 inuse = READ_ONCE(child->inuse);
 
@@ -993,11 +993,11 @@ static void current_hweight(struct ioc_gq *iocg, u32 *hw_activep, u32 *hw_inusep
 		if (!active_sum || !inuse_sum)
 			continue;
 
-		active_sum = max(active, active_sum);
-		hwa = hwa * active / active_sum;	/* max 16bits * 10000 */
+		active_sum = max_t(u64, active, active_sum);
+		hwa = div64_u64((u64)hwa * active, active_sum);
 
-		inuse_sum = max(inuse, inuse_sum);
-		hwi = hwi * inuse / inuse_sum;		/* max 16bits * 10000 */
+		inuse_sum = max_t(u64, inuse, inuse_sum);
+		hwi = div64_u64((u64)hwi * inuse, inuse_sum);
 	}
 
 	iocg->hweight_active = max_t(u32, hwa, 1);
@@ -1022,7 +1022,8 @@ static void weight_updated(struct ioc_gq *iocg)
 	weight = iocg->cfg_weight ?: iocc->dfl_weight;
 	if (weight != iocg->weight && iocg->active)
 		propagate_weights(iocg, weight,
-			DIV64_U64_ROUND_UP(iocg->inuse * weight, iocg->weight));
+				  DIV64_U64_ROUND_UP((u64)iocg->inuse * weight,
+						     iocg->weight));
 	iocg->weight = weight;
 }
 
@@ -2050,7 +2051,7 @@ static struct blkcg_policy_data *ioc_cpd_alloc(gfp_t gfp)
 	if (!iocc)
 		return NULL;
 
-	iocc->dfl_weight = CGROUP_WEIGHT_DFL;
+	iocc->dfl_weight = CGROUP_WEIGHT_DFL * WEIGHT_ONE;
 	return &iocc->cpd;
 }
 
@@ -2136,7 +2137,7 @@ static u64 ioc_weight_prfill(struct seq_file *sf, struct blkg_policy_data *pd,
 	struct ioc_gq *iocg = pd_to_iocg(pd);
 
 	if (dname && iocg->cfg_weight)
-		seq_printf(sf, "%s %u\n", dname, iocg->cfg_weight);
+		seq_printf(sf, "%s %u\n", dname, iocg->cfg_weight / WEIGHT_ONE);
 	return 0;
 }
 
@@ -2146,7 +2147,7 @@ static int ioc_weight_show(struct seq_file *sf, void *v)
 	struct blkcg *blkcg = css_to_blkcg(seq_css(sf));
 	struct ioc_cgrp *iocc = blkcg_to_iocc(blkcg);
 
-	seq_printf(sf, "default %u\n", iocc->dfl_weight);
+	seq_printf(sf, "default %u\n", iocc->dfl_weight / WEIGHT_ONE);
 	blkcg_print_blkgs(sf, blkcg, ioc_weight_prfill,
 			  &blkcg_policy_iocost, seq_cft(sf)->private, false);
 	return 0;
@@ -2172,7 +2173,7 @@ static ssize_t ioc_weight_write(struct kernfs_open_file *of, char *buf,
 			return -EINVAL;
 
 		spin_lock(&blkcg->lock);
-		iocc->dfl_weight = v;
+		iocc->dfl_weight = v * WEIGHT_ONE;
 		hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) {
 			struct ioc_gq *iocg = blkg_to_iocg(blkg);
 
@@ -2203,7 +2204,7 @@ static ssize_t ioc_weight_write(struct kernfs_open_file *of, char *buf,
 	}
 
 	spin_lock(&iocg->ioc->lock);
-	iocg->cfg_weight = v;
+	iocg->cfg_weight = v * WEIGHT_ONE;
 	weight_updated(iocg);
 	spin_unlock(&iocg->ioc->lock);
 
-- 
2.26.2


  parent reply	other threads:[~2020-09-01 18:53 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-01 18:52 [PATCHSET for-5.10/block] blk-iocost: iocost: improve donation, debt and excess handling Tejun Heo
2020-09-01 18:52 ` [PATCH 01/27] blk-iocost: ioc_pd_free() shouldn't assume irq disabled Tejun Heo
2020-09-01 18:52 ` [PATCH 02/27] blk-stat: make q->stats->lock irqsafe Tejun Heo
2020-09-01 18:52 ` [PATCH 03/27] blk-iocost: use local[64]_t for percpu stat Tejun Heo
2020-11-20 21:51   ` Stafford Horne
2020-11-20 22:13     ` Tejun Heo
2020-09-01 18:52 ` [PATCH 04/27] blk-iocost: rename propagate_active_weights() to propagate_weights() Tejun Heo
2020-09-01 18:52 ` [PATCH 05/27] blk-iocost: clamp inuse and skip noops in __propagate_weights() Tejun Heo
2020-09-01 18:52 ` [PATCH 06/27] blk-iocost: move iocg_kick_delay() above iocg_kick_waitq() Tejun Heo
2020-09-01 18:52 ` [PATCH 07/27] blk-iocost: make iocg_kick_waitq() call iocg_kick_delay() after paying debt Tejun Heo
2020-09-01 18:52 ` [PATCH 08/27] blk-iocost: s/HWEIGHT_WHOLE/WEIGHT_ONE/g Tejun Heo
2020-09-01 18:52 ` Tejun Heo [this message]
2020-09-01 18:52 ` [PATCH 10/27] blk-iocost: make ioc_now->now and ioc->period_at 64bit Tejun Heo
2020-09-01 18:52 ` [PATCH 11/27] blk-iocost: streamline vtime margin and timer slack handling Tejun Heo
2020-09-01 18:52 ` [PATCH 12/27] blk-iocost: grab ioc->lock for debt handling Tejun Heo
2020-09-01 18:52 ` [PATCH 13/27] blk-iocost: add absolute usage stat Tejun Heo
2020-09-01 18:52 ` [PATCH 14/27] blk-iocost: calculate iocg->usages[] from iocg->local_stat.usage_us Tejun Heo
2020-09-01 18:52 ` [PATCH 15/27] blk-iocost: replace iocg->has_surplus with ->surplus_list Tejun Heo
2020-09-01 18:52 ` [PATCH 16/27] blk-iocost: decouple vrate adjustment from surplus transfers Tejun Heo
2020-09-01 18:52 ` [PATCH 17/27] blk-iocost: restructure surplus donation logic Tejun Heo
2020-09-01 18:52 ` [PATCH 18/27] blk-iocost: implement Andy's method for donation weight updates Tejun Heo
2020-09-01 18:52 ` [PATCH 19/27] blk-iocost: revamp donation amount determination Tejun Heo
2020-09-01 18:52 ` [PATCH 20/27] blk-iocost: revamp in-period donation snapbacks Tejun Heo
2020-09-01 18:52 ` [PATCH 21/27] blk-iocost: revamp debt handling Tejun Heo
2020-09-01 18:52 ` [PATCH 22/27] blk-iocost: implement delay adjustment hysteresis Tejun Heo
2020-09-01 18:52 ` [PATCH 23/27] blk-iocost: halve debts if device stays idle Tejun Heo
2020-09-01 18:52 ` [PATCH 24/27] blk-iocost: implement vtime loss compensation Tejun Heo
2020-09-01 18:52 ` [PATCH 25/27] blk-iocost: restore inuse update tracepoints Tejun Heo
2020-09-01 18:52 ` [PATCH 26/27] blk-iocost: add three debug stat - cost.wait, indebt and indelay Tejun Heo
2020-09-01 18:52 ` [PATCH 27/27] blk-iocost: update iocost_monitor.py Tejun Heo
2020-09-01 22:57 ` [PATCHSET for-5.10/block] blk-iocost: iocost: improve donation, debt and excess handling Jens Axboe

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