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Commit 41b38b6d authored by Tejun Heo's avatar Tejun Heo
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blkcg: cfq doesn't need per-cpu dispatch stats 



blkio_group_stats_cpu is used to count dispatch stats using per-cpu
counters.  This is used by both blk-throtl and cfq-iosched but the
sharing is rather silly.

* cfq-iosched doesn't need per-cpu dispatch stats.  cfq always updates
  those stats while holding queue_lock.

* blk-throtl needs per-cpu dispatch stats but only service_bytes and
  serviced.  It doesn't make use of sectors.

This patch makes cfq add and use global stats for service_bytes,
serviced and sectors, removes per-cpu sectors counter and moves
per-cpu stat printing code to blk-throttle.c.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent 629ed0b1

block/blk-cgroup.c

+2 −61
Original line number Diff line number Diff line
@@ -390,7 +390,6 @@ static void blkio_reset_stats_cpu(struct blkio_group *blkg, int plid) 


		blkg_rwstat_reset(&sc->service_bytes);

		blkg_rwstat_reset(&sc->serviced);

		blkg_stat_reset(&sc->sectors);

	}

}
@@ -417,6 +416,8 @@ blkiocg_reset_stats(struct cgroup *cgroup, struct cftype *cftype, u64 val) 
			struct blkio_group_stats *stats = &pd->stats;



			/* queued stats shouldn't be cleared */

			blkg_rwstat_reset(&stats->service_bytes);

			blkg_rwstat_reset(&stats->serviced);

			blkg_rwstat_reset(&stats->merged);

			blkg_rwstat_reset(&stats->service_time);

			blkg_rwstat_reset(&stats->wait_time);
@@ -577,66 +578,6 @@ int blkcg_print_rwstat(struct cgroup *cgrp, struct cftype *cft, 
}

EXPORT_SYMBOL_GPL(blkcg_print_rwstat);



static u64 blkg_prfill_cpu_stat(struct seq_file *sf,

				struct blkg_policy_data *pd, int off)

{

	u64 v = 0;

	int cpu;



	for_each_possible_cpu(cpu) {

		struct blkio_group_stats_cpu *sc =

			per_cpu_ptr(pd->stats_cpu, cpu);



		v += blkg_stat_read((void *)sc + off);

	}



	return __blkg_prfill_u64(sf, pd, v);

}



static u64 blkg_prfill_cpu_rwstat(struct seq_file *sf,

				  struct blkg_policy_data *pd, int off)

{

	struct blkg_rwstat rwstat = { }, tmp;

	int i, cpu;



	for_each_possible_cpu(cpu) {

		struct blkio_group_stats_cpu *sc =

			per_cpu_ptr(pd->stats_cpu, cpu);



		tmp = blkg_rwstat_read((void *)sc + off);

		for (i = 0; i < BLKG_RWSTAT_NR; i++)

			rwstat.cnt[i] += tmp.cnt[i];

	}



	return __blkg_prfill_rwstat(sf, pd, &rwstat);

}



/* print per-cpu blkg_stat specified by BLKCG_STAT_PRIV() */

int blkcg_print_cpu_stat(struct cgroup *cgrp, struct cftype *cft,

			 struct seq_file *sf)

{

	struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgrp);



	blkcg_print_blkgs(sf, blkcg, blkg_prfill_cpu_stat,

			  BLKCG_STAT_POL(cft->private),

			  BLKCG_STAT_OFF(cft->private), false);

	return 0;

}

EXPORT_SYMBOL_GPL(blkcg_print_cpu_stat);



/* print per-cpu blkg_rwstat specified by BLKCG_STAT_PRIV() */

int blkcg_print_cpu_rwstat(struct cgroup *cgrp, struct cftype *cft,

			   struct seq_file *sf)

{

	struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgrp);



	blkcg_print_blkgs(sf, blkcg, blkg_prfill_cpu_rwstat,

			  BLKCG_STAT_POL(cft->private),

			  BLKCG_STAT_OFF(cft->private), true);

	return 0;

}

EXPORT_SYMBOL_GPL(blkcg_print_cpu_rwstat);



/**

 * blkg_conf_prep - parse and prepare for per-blkg config update

 * @blkcg: target block cgroup

block/blk-cgroup.h

+6 −6
Original line number Diff line number Diff line
@@ -65,6 +65,10 @@ struct blkg_rwstat { 
};



struct blkio_group_stats {

	/* total bytes transferred */

	struct blkg_rwstat		service_bytes;

	/* total IOs serviced, post merge */

	struct blkg_rwstat		serviced;

	/* number of ios merged */

	struct blkg_rwstat		merged;

	/* total time spent on device in ns, may not be accurate w/ queueing */
@@ -73,6 +77,8 @@ struct blkio_group_stats { 
	struct blkg_rwstat		wait_time;

	/* number of IOs queued up */

	struct blkg_rwstat		queued;

	/* total sectors transferred */

	struct blkg_stat		sectors;

	/* total disk time and nr sectors dispatched by this group */

	struct blkg_stat		time;

#ifdef CONFIG_DEBUG_BLK_CGROUP
@@ -104,8 +110,6 @@ struct blkio_group_stats_cpu { 
	struct blkg_rwstat		service_bytes;

	/* total IOs serviced, post merge */

	struct blkg_rwstat		serviced;

	/* total sectors transferred */

	struct blkg_stat		sectors;

};



struct blkio_group_conf {
@@ -183,10 +187,6 @@ int blkcg_print_stat(struct cgroup *cgrp, struct cftype *cft, 
		     struct seq_file *sf);

int blkcg_print_rwstat(struct cgroup *cgrp, struct cftype *cft,

		       struct seq_file *sf);

int blkcg_print_cpu_stat(struct cgroup *cgrp, struct cftype *cft,

			 struct seq_file *sf);

int blkcg_print_cpu_rwstat(struct cgroup *cgrp, struct cftype *cft,

			   struct seq_file *sf);



struct blkg_conf_ctx {

	struct gendisk		*disk;

block/blk-throttle.c

+30 −1
Original line number Diff line number Diff line
@@ -582,7 +582,6 @@ static void throtl_update_dispatch_stats(struct blkio_group *blkg, u64 bytes, 


	stats_cpu = this_cpu_ptr(pd->stats_cpu);



	blkg_stat_add(&stats_cpu->sectors, bytes >> 9);

	blkg_rwstat_add(&stats_cpu->serviced, rw, 1);

	blkg_rwstat_add(&stats_cpu->service_bytes, rw, bytes);
@@ -843,6 +842,36 @@ static void throtl_update_blkio_group_common(struct throtl_data *td, 
	throtl_schedule_delayed_work(td, 0);

}



static u64 blkg_prfill_cpu_rwstat(struct seq_file *sf,

				  struct blkg_policy_data *pd, int off)

{

	struct blkg_rwstat rwstat = { }, tmp;

	int i, cpu;



	for_each_possible_cpu(cpu) {

		struct blkio_group_stats_cpu *sc =

			per_cpu_ptr(pd->stats_cpu, cpu);



		tmp = blkg_rwstat_read((void *)sc + off);

		for (i = 0; i < BLKG_RWSTAT_NR; i++)

			rwstat.cnt[i] += tmp.cnt[i];

	}



	return __blkg_prfill_rwstat(sf, pd, &rwstat);

}



/* print per-cpu blkg_rwstat specified by BLKCG_STAT_PRIV() */

static int blkcg_print_cpu_rwstat(struct cgroup *cgrp, struct cftype *cft,

				  struct seq_file *sf)

{

	struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgrp);



	blkcg_print_blkgs(sf, blkcg, blkg_prfill_cpu_rwstat,

			  BLKCG_STAT_POL(cft->private),

			  BLKCG_STAT_OFF(cft->private), true);

	return 0;

}



static u64 blkg_prfill_conf_u64(struct seq_file *sf,

				struct blkg_policy_data *pd, int off)

{

block/cfq-iosched.c

+10 −27
Original line number Diff line number Diff line
@@ -624,29 +624,12 @@ static inline void cfq_blkiocg_update_dispatch_stats(struct blkio_group *blkg, 
			struct blkio_policy_type *pol, uint64_t bytes,

			bool direction, bool sync)

{

	struct blkio_group_stats *stats = &blkg->pd[pol->plid]->stats;

	int rw = (direction ? REQ_WRITE : 0) | (sync ? REQ_SYNC : 0);

	struct blkg_policy_data *pd = blkg->pd[pol->plid];

	struct blkio_group_stats_cpu *stats_cpu;

	unsigned long flags;



	/* If per cpu stats are not allocated yet, don't do any accounting. */

	if (pd->stats_cpu == NULL)

		return;



	/*

	 * Disabling interrupts to provide mutual exclusion between two

	 * writes on same cpu. It probably is not needed for 64bit. Not

	 * optimizing that case yet.

	 */

	local_irq_save(flags);



	stats_cpu = this_cpu_ptr(pd->stats_cpu);



	blkg_stat_add(&stats_cpu->sectors, bytes >> 9);

	blkg_rwstat_add(&stats_cpu->serviced, rw, 1);

	blkg_rwstat_add(&stats_cpu->service_bytes, rw, bytes);



	local_irq_restore(flags);

	blkg_stat_add(&stats->sectors, bytes >> 9);

	blkg_rwstat_add(&stats->serviced, rw, 1);

	blkg_rwstat_add(&stats->service_bytes, rw, bytes);

}



static inline void cfq_blkiocg_update_completion_stats(struct blkio_group *blkg,
@@ -1520,20 +1503,20 @@ static struct cftype cfq_blkcg_files[] = { 
	{

		.name = "sectors",

		.private = BLKCG_STAT_PRIV(BLKIO_POLICY_PROP,

				offsetof(struct blkio_group_stats_cpu, sectors)),

		.read_seq_string = blkcg_print_cpu_stat,

				offsetof(struct blkio_group_stats, sectors)),

		.read_seq_string = blkcg_print_stat,

	},

	{

		.name = "io_service_bytes",

		.private = BLKCG_STAT_PRIV(BLKIO_POLICY_PROP,

				offsetof(struct blkio_group_stats_cpu, service_bytes)),

		.read_seq_string = blkcg_print_cpu_rwstat,

				offsetof(struct blkio_group_stats, service_bytes)),

		.read_seq_string = blkcg_print_rwstat,

	},

	{

		.name = "io_serviced",

		.private = BLKCG_STAT_PRIV(BLKIO_POLICY_PROP,

				offsetof(struct blkio_group_stats_cpu, serviced)),

		.read_seq_string = blkcg_print_cpu_rwstat,

				offsetof(struct blkio_group_stats, serviced)),

		.read_seq_string = blkcg_print_rwstat,

	},

	{

		.name = "io_service_time",