We know total bandwidth of a disk and can calculate cgroup's bandwidth
percentage against disk bandwidth according to its weight. We can easily
calculate cgroup bandwidth.
Signed-off-by: Shaohua Li <s...@fb.com>
---
block/blk-throttle.c | 160 +++++++++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 156 insertions(+), 4 deletions(-)
diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index 90f937f..fafe9c2 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -2,6 +2,7 @@
* Interface for controlling IO bandwidth on a request queue
*
* Copyright (C) 2010 Vivek Goyal <vgo...@redhat.com>
+ * Proportional throttle - Shaohua Li <s...@kernel.org>
*/
#include <linux/module.h>
@@ -12,6 +13,12 @@
#include <linux/blk-cgroup.h>
#include "blk.h"
+#define MAX_WEIGHT (10000)
+#define MIN_WEIGHT (1)
+#define DFT_WEIGHT (100)
+#define SHARE_SHIFT (14)
+#define MAX_SHARE (1 << SHARE_SHIFT)
+
/* Max dispatch from a group in 1 round */
static int throtl_grp_quantum = 8;
@@ -74,6 +81,10 @@ struct throtl_service_queue {
unsigned int nr_pending; /* # queued in the tree */
unsigned long first_pending_disptime; /* disptime of the
first tg */
struct timer_list pending_timer; /* fires on
first_pending_disptime */
+
+ unsigned int weight; /* this queue's weight against siblings
*/
+ unsigned int children_weight; /* children weight */
+ unsigned int share; /* disk bandwidth share of the queue */
};
enum tg_state_flags {
@@ -139,6 +150,22 @@ struct throtl_grp {
unsigned long slice_end[2];
};
+enum run_mode {
+ MODE_NONE = 0,
+ MODE_THROTTLE = 1, /* bandwidth/iops based throttle */
+ /* below are weight based */
+ MODE_WEIGHT_BANDWIDTH = 2,
+ MODE_WEIGHT_IOPS = 3,
+ MAX_MODE = 4,
+};
+
+static char *run_mode_name[MAX_MODE] = {
+ [MODE_NONE] = "none",
+ [MODE_THROTTLE] = "throttle",
+ [MODE_WEIGHT_BANDWIDTH] = "weight_bw",
+ [MODE_WEIGHT_IOPS] = "weight_iops",
+};
+
struct throtl_data
{
/* service tree for active throtl groups */
@@ -156,8 +183,14 @@ struct throtl_data
/* Work for dispatching throttled bios */
struct work_struct dispatch_work;
+ enum run_mode mode;
};
+static bool td_weight_based(struct throtl_data *td)
+{
+ return td->mode > MODE_THROTTLE;
+}
+
static void throtl_pending_timer_fn(unsigned long arg);
static inline struct throtl_grp *pd_to_tg(struct blkg_policy_data *pd)
@@ -209,9 +242,33 @@ static struct throtl_data *sq_to_td(struct
throtl_service_queue *sq)
static inline int tg_data_index(struct throtl_grp *tg, bool rw)
{
+ if (td_weight_based(tg->td))
+ return 0;
return rw;
}
+static inline uint64_t queue_bandwidth(struct throtl_data *td)
+{
+ uint64_t bw;
+
+ bw = td->queue->disk_bw * 512;
+ /* can't estimate bandwidth, can't do proporation control */
+ if (bw == 0)
+ bw = -1;
+ return bw;
+}
+
+static inline uint64_t queue_iops(struct throtl_data *td)
+{
+ uint64_t iops;
+
+ iops = td->queue->disk_iops;
+ /* can't estimate iops, can't do proporation control */
+ if (iops == 0)
+ iops = -1;
+ return iops;
+}
+
/**
* throtl_log - log debug message via blktrace
* @sq: the service_queue being reported
@@ -386,6 +443,8 @@ static void throtl_pd_init(struct blkg_policy_data *pd)
sq->parent_sq = &td->service_queue;
if (cgroup_subsys_on_dfl(io_cgrp_subsys) && blkg->parent)
sq->parent_sq = &blkg_to_tg(blkg->parent)->service_queue;
+ sq->weight = DFT_WEIGHT;
+ sq->parent_sq->children_weight += sq->weight;
tg->td = td;
}
@@ -406,7 +465,8 @@ static void tg_update_has_rules(struct throtl_grp *tg)
for (i = READ; i <= WRITE; i++)
tg->has_rules[i] = (parent_tg && parent_tg->has_rules[i]) ||
- io_cost_has_limit(tg, i);
+ io_cost_has_limit(tg, i) ||
+ (td_weight_based(tg->td));
}
static void throtl_pd_online(struct blkg_policy_data *pd)
@@ -421,6 +481,10 @@ static void throtl_pd_online(struct blkg_policy_data *pd)
static void throtl_pd_free(struct blkg_policy_data *pd)
{
struct throtl_grp *tg = pd_to_tg(pd);
+ struct throtl_service_queue *sq = &tg->service_queue;
+
+ if (sq->parent_sq)
+ sq->parent_sq->children_weight -= sq->weight;
del_timer_sync(&tg->service_queue.pending_timer);
kfree(tg);
@@ -812,6 +876,10 @@ static bool io_cost_with_in_limit(struct throtl_grp *tg,
struct bio *bio,
{
unsigned long bps_wait = 0, iops_wait = 0;
+ if (tg->td->mode == MODE_WEIGHT_BANDWIDTH)
+ return io_cost_with_in_bps_limit(tg, bio, wait);
+ if (tg->td->mode == MODE_WEIGHT_IOPS)
+ return io_cost_with_in_iops_limit(tg, bio, wait);
if (io_cost_with_in_bps_limit(tg, bio, &bps_wait) &&
io_cost_with_in_iops_limit(tg, bio, &iops_wait)) {
*wait = 0;
@@ -967,6 +1035,77 @@ static void start_parent_slice_with_credit(struct
throtl_grp *child_tg,
}
+static void tg_update_perf(struct throtl_grp *tg)
+{
+ struct throtl_service_queue *sq;
+ u64 new_bps, abs_bps = 0;
+ unsigned int new_iops, abs_iops = 0;
+
+ sq = &tg->service_queue;
+
+ /* '/' cgroup in cgroup2 */
+ if (!td_weight_based(tg->td) || !sq->parent_sq ||
+ (cgroup_subsys_on_dfl(io_cgrp_subsys) && !tg_to_blkg(tg)->parent))
+ return;
+
+ if (tg->td->mode == MODE_WEIGHT_BANDWIDTH) {
+ new_bps = max_t(uint64_t,
+ (queue_bandwidth(tg->td) * sq->share) >> SHARE_SHIFT,
+ 1024);
+ if (new_bps > tg->io_cost.bps[0])
+ abs_bps = new_bps - tg->io_cost.bps[0];
+ if (new_bps < tg->io_cost.bps[0])
+ abs_bps = tg->io_cost.bps[0] - new_bps;
+ if (abs_bps > (tg->io_cost.bps[0] >> 3))
+ throtl_start_new_slice(tg, 0);
+ tg->io_cost.bps[0] = new_bps;
+ tg->io_cost.iops[0] = -1;
+ } else {
+ new_iops = max_t(uint64_t,
+ (queue_iops(tg->td) * sq->share) >> SHARE_SHIFT,
+ 1);
+ if (new_iops > tg->io_cost.iops[0])
+ abs_iops = new_iops - tg->io_cost.iops[0];
+ if (new_iops < tg->io_cost.iops[0])
+ abs_iops = tg->io_cost.iops[0] - new_iops;
+ if (abs_iops > (tg->io_cost.iops[0] >> 3))
+ throtl_start_new_slice(tg, 0);
+ tg->io_cost.iops[0] = new_iops;
+ tg->io_cost.bps[0] = -1;
+ }
+}
+
+/* update share of tg's siblings */
+static void tg_update_share(struct throtl_data *td, struct throtl_grp *tg)
+{
+ struct cgroup_subsys_state *pos_css;
+ struct blkcg_gq *blkg, *parent_blkg;
+ struct throtl_grp *child;
+
+ if (!td_weight_based(td))
+ return;
+ if (!tg || !tg->service_queue.parent_sq ||
+ !tg->service_queue.parent_sq->parent_sq)
+ parent_blkg = td->queue->root_blkg;
+ else
+ parent_blkg = tg_to_blkg(sq_to_tg(tg->service_queue.parent_sq));
+
+ blkg_for_each_descendant_pre(blkg, pos_css, parent_blkg) {
+ struct throtl_service_queue *sq;
+
+ child = blkg_to_tg(blkg);
+ sq = &child->service_queue;
+
+ if (!sq->parent_sq)
+ continue;
+
+ sq->share = max_t(unsigned int,
+ sq->parent_sq->share * sq->weight /
+ sq->parent_sq->children_weight,
+ 1);
+ }
+}
+
static void tg_dispatch_one_bio(struct throtl_grp *tg, bool rw)
{
struct throtl_service_queue *sq = &tg->service_queue;
@@ -1014,11 +1153,18 @@ static int throtl_dispatch_tg(struct throtl_grp *tg)
{
struct throtl_service_queue *sq = &tg->service_queue;
unsigned int nr_reads = 0, nr_writes = 0;
- unsigned int max_nr_reads = throtl_grp_quantum*3/4;
- unsigned int max_nr_writes = throtl_grp_quantum - max_nr_reads;
+ unsigned int max_nr_reads;
+ unsigned int max_nr_writes;
struct bio *bio;
- /* Try to dispatch 75% READS and 25% WRITES */
+ if (td_weight_based(tg->td)) {
+ max_nr_reads = throtl_grp_quantum;
+ max_nr_writes = 0;
+ } else {
+ /* Try to dispatch 75% READS and 25% WRITES */
+ max_nr_reads = throtl_grp_quantum * 3 / 4;
+ max_nr_writes = throtl_grp_quantum - max_nr_reads;
+ }
while ((bio = throtl_peek_queued(&sq->queued[READ])) &&
tg_may_dispatch(tg, bio, NULL)) {
@@ -1039,6 +1185,9 @@ static int throtl_dispatch_tg(struct throtl_grp *tg)
if (nr_writes >= max_nr_writes)
break;
}
+ if (nr_reads + nr_writes) {
+ tg_update_perf(tg);
+ }
return nr_reads + nr_writes;
}
@@ -1494,6 +1643,7 @@ bool blk_throtl_bio(struct request_queue *q, struct
blkcg_gq *blkg,
/* throtl is FIFO - if bios are already queued, should queue */
if (sq->nr_queued[index])
break;
+ tg_update_perf(tg);
/* if above limits, break to queue */
if (!tg_may_dispatch(tg, bio, NULL))
@@ -1639,6 +1789,8 @@ int blk_throtl_init(struct request_queue *q)
INIT_WORK(&td->dispatch_work, blk_throtl_dispatch_work_fn);
throtl_service_queue_init(&td->service_queue);
+ td->service_queue.share = MAX_SHARE;
+ td->mode = MODE_NONE;
q->td = td;
td->queue = q;
--
2.6.5
