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bfq: Add per-device weight

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This adds to BFQ the missing per-device weight interfaces:
blkio.bfq.weight_device on legacy and io.bfq.weight on unified. The
implementation pretty closely resembles what we had in CFQ and the parsing code
is basically reused.

Tests
=====

Using two cgroups and three block devices, having weights setup as:

Cgroup          test1           test2
============================================
default         100             500
sda             500             100
sdb             default         default
sdc             200             200

cgroup v1 runs
--------------

    sda.test1.out:   READ: bw=913MiB/s
    sda.test2.out:   READ: bw=183MiB/s

    sdb.test1.out:   READ: bw=213MiB/s
    sdb.test2.out:   READ: bw=1054MiB/s

    sdc.test1.out:   READ: bw=650MiB/s
    sdc.test2.out:   READ: bw=650MiB/s

cgroup v2 runs
--------------

    sda.test1.out:   READ: bw=915MiB/s
    sda.test2.out:   READ: bw=184MiB/s

    sdb.test1.out:   READ: bw=216MiB/s
    sdb.test2.out:   READ: bw=1069MiB/s

    sdc.test1.out:   READ: bw=621MiB/s
    sdc.test2.out:   READ: bw=622MiB/s

Signed-off-by: Fam Zheng <zhengfeiran@bytedance.com>
Acked-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Paolo Valente <paolo.valente@linaro.org>

Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Fam Zheng 2019-08-28 11:54:53 +08:00 committed by Jens Axboe
parent 5ff047e328
commit 795fe54c2a
2 changed files with 87 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

95
block/bfq-cgroup.c
View File

@ -905,7 +905,7 @@ void bfq_end_wr_async(struct bfq_data *bfqd)
bfq_end_wr_async_queues(bfqd, bfqd->root_group);
}
static int bfq_io_show_weight(struct seq_file *sf, void *v)
static int bfq_io_show_weight_legacy(struct seq_file *sf, void *v)
{
struct blkcg *blkcg = css_to_blkcg(seq_css(sf));
struct bfq_group_data *bfqgd = blkcg_to_bfqgd(blkcg);
@ -919,8 +919,32 @@ static int bfq_io_show_weight(struct seq_file *sf, void *v)
return 0;
}
static void bfq_group_set_weight(struct bfq_group *bfqg, u64 weight)
static u64 bfqg_prfill_weight_device(struct seq_file *sf,
struct blkg_policy_data *pd, int off)
{
struct bfq_group *bfqg = pd_to_bfqg(pd);
if (!bfqg->entity.dev_weight)
return 0;
return __blkg_prfill_u64(sf, pd, bfqg->entity.dev_weight);
}
static int bfq_io_show_weight(struct seq_file *sf, void *v)
{
struct blkcg *blkcg = css_to_blkcg(seq_css(sf));
struct bfq_group_data *bfqgd = blkcg_to_bfqgd(blkcg);
seq_printf(sf, "default %u\n", bfqgd->weight);
blkcg_print_blkgs(sf, blkcg, bfqg_prfill_weight_device,
&blkcg_policy_bfq, 0, false);
return 0;
}
static void bfq_group_set_weight(struct bfq_group *bfqg, u64 weight, u64 dev_weight)
{
weight = dev_weight ?: weight;
bfqg->entity.dev_weight = dev_weight;
/*
* Setting the prio_changed flag of the entity
* to 1 with new_weight == weight would re-set
@ -968,26 +992,69 @@ static int bfq_io_set_weight_legacy(struct cgroup_subsys_state *css,
struct bfq_group *bfqg = blkg_to_bfqg(blkg);
if (bfqg)
bfq_group_set_weight(bfqg, val);
bfq_group_set_weight(bfqg, val, 0);
}
spin_unlock_irq(&blkcg->lock);
return ret;
}
static ssize_t bfq_io_set_device_weight(struct kernfs_open_file *of,
char *buf, size_t nbytes,
loff_t off)
{
int ret;
struct blkg_conf_ctx ctx;
struct blkcg *blkcg = css_to_blkcg(of_css(of));
struct bfq_group *bfqg;
u64 v;
ret = blkg_conf_prep(blkcg, &blkcg_policy_bfq, buf, &ctx);
if (ret)
return ret;
if (sscanf(ctx.body, "%llu", &v) == 1) {
/* require "default" on dfl */
ret = -ERANGE;
if (!v)
goto out;
} else if (!strcmp(strim(ctx.body), "default")) {
v = 0;
} else {
ret = -EINVAL;
goto out;
}
bfqg = blkg_to_bfqg(ctx.blkg);
ret = -ERANGE;
if (!v || (v >= BFQ_MIN_WEIGHT && v <= BFQ_MAX_WEIGHT)) {
bfq_group_set_weight(bfqg, bfqg->entity.weight, v);
ret = 0;
}
out:
blkg_conf_finish(&ctx);
return ret ?: nbytes;
}
static ssize_t bfq_io_set_weight(struct kernfs_open_file *of,
char *buf, size_t nbytes,
loff_t off)
{
u64 weight;
/* First unsigned long found in the file is used */
int ret = kstrtoull(strim(buf), 0, &weight);
char *endp;
int ret;
u64 v;
if (ret)
return ret;
buf = strim(buf);
ret = bfq_io_set_weight_legacy(of_css(of), NULL, weight);
return ret ?: nbytes;
/* "WEIGHT" or "default WEIGHT" sets the default weight */
v = simple_strtoull(buf, &endp, 0);
if (*endp == '\0' || sscanf(buf, "default %llu", &v) == 1) {
ret = bfq_io_set_weight_legacy(of_css(of), NULL, v);
return ret ?: nbytes;
}
return bfq_io_set_device_weight(of, buf, nbytes, off);
}
#ifdef CONFIG_BFQ_CGROUP_DEBUG
@ -1146,9 +1213,15 @@ struct cftype bfq_blkcg_legacy_files[] = {
{
.name = "bfq.weight",
.flags = CFTYPE_NOT_ON_ROOT,
.seq_show = bfq_io_show_weight,
.seq_show = bfq_io_show_weight_legacy,
.write_u64 = bfq_io_set_weight_legacy,
},
{
.name = "bfq.weight_device",
.flags = CFTYPE_NOT_ON_ROOT,
.seq_show = bfq_io_show_weight,
.write = bfq_io_set_weight,
},
/* statistics, covers only the tasks in the bfqg */
{

3
block/bfq-iosched.h
View File

@ -168,6 +168,9 @@ struct bfq_entity {
/* budget, used also to calculate F_i: F_i = S_i + @budget / @weight */
int budget;
/* device weight, if non-zero, it overrides the default weight of
* bfq_group_data */
int dev_weight;
/* weight of the queue */
int weight;
/* next weight if a change is in progress */