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Commit 795fe54c authored by Fam Zheng's avatar Fam Zheng Committed by Jens Axboe
Browse files

bfq: Add per-device weight 



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: default avatarFam Zheng <zhengfeiran@bytedance.com>
Acked-by: default avatarTejun Heo <tj@kernel.org>
Reviewed-by: default avatarPaolo Valente <paolo.valente@linaro.org>

Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 5ff047e3

block/bfq-cgroup.c

+84 −11
Original line number Diff line number Diff line
@@ -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
@@ -968,28 +992,71 @@ 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_weight(struct kernfs_open_file *of,

static ssize_t bfq_io_set_device_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);

	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;



	ret = bfq_io_set_weight_legacy(of_css(of), NULL, weight);

	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)

{

	char *endp;

	int ret;

	u64 v;



	buf = strim(buf);



	/* "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

static int bfqg_print_stat(struct seq_file *sf, void *v)

{
@@ -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 */

	{

block/bfq-iosched.h

+3 −0
Original line number Diff line number Diff line
@@ -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 */