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Commit 903d23f0 authored by Josef Bacik's avatar Josef Bacik Committed by Jens Axboe
Browse files

blk-cgroup: allow controllers to output their own stats 



blk-iolatency has a few stats that it would like to print out, and
instead of adding a bunch of crap to the generic code just provide a
helper so that controllers can add stuff to the stat line if they want
to.

Hide it behind a boot option since it changes the output of io.stat from
normal, and these stats are only interesting to developers.

Signed-off-by: default avatarJosef Bacik <jbacik@fb.com>
Acked-by: default avatarTejun Heo <tj@kernel.org>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent c7c98fd3

block/blk-cgroup.c

+44 −3
Original line number Diff line number Diff line
@@ -50,6 +50,8 @@ static struct blkcg_policy *blkcg_policy[BLKCG_MAX_POLS]; 


static LIST_HEAD(all_blkcgs);		/* protected by blkcg_pol_mutex */



static bool blkcg_debug_stats = false;



static bool blkcg_policy_enabled(struct request_queue *q,

				 const struct blkcg_policy *pol)

{
@@ -954,13 +956,25 @@ static int blkcg_print_stat(struct seq_file *sf, void *v) 


	hlist_for_each_entry_rcu(blkg, &blkcg->blkg_list, blkcg_node) {

		const char *dname;

		char *buf;

		struct blkg_rwstat rwstat;

		u64 rbytes, wbytes, rios, wios;

		size_t size = seq_get_buf(sf, &buf), off = 0;

		int i;

		bool has_stats = false;



		dname = blkg_dev_name(blkg);

		if (!dname)

			continue;



		/*

		 * Hooray string manipulation, count is the size written NOT

		 * INCLUDING THE \0, so size is now count+1 less than what we

		 * had before, but we want to start writing the next bit from

		 * the \0 so we only add count to buf.

		 */

		off += scnprintf(buf+off, size-off, "%s ", dname);



		spin_lock_irq(blkg->q->queue_lock);



		rwstat = blkg_rwstat_recursive_sum(blkg, NULL,
@@ -975,9 +989,33 @@ static int blkcg_print_stat(struct seq_file *sf, void *v) 


		spin_unlock_irq(blkg->q->queue_lock);



		if (rbytes || wbytes || rios || wios)

			seq_printf(sf, "%s rbytes=%llu wbytes=%llu rios=%llu wios=%llu\n",

				   dname, rbytes, wbytes, rios, wios);

		if (rbytes || wbytes || rios || wios) {

			has_stats = true;

			off += scnprintf(buf+off, size-off,

					 "rbytes=%llu wbytes=%llu rios=%llu wios=%llu",

					 rbytes, wbytes, rios, wios);

		}



		if (!blkcg_debug_stats)

			goto next;



		for (i = 0; i < BLKCG_MAX_POLS; i++) {

			struct blkcg_policy *pol = blkcg_policy[i];

			size_t written;



			if (!blkg->pd[i] || !pol->pd_stat_fn)

				continue;



			written = pol->pd_stat_fn(blkg->pd[i], buf+off, size-off);

			if (written)

				has_stats = true;

			off += written;

		}

next:

		if (has_stats) {

			off += scnprintf(buf+off, size-off, "\n");

			seq_commit(sf, off);

		}

	}



	rcu_read_unlock();
@@ -1547,3 +1585,6 @@ void blkcg_policy_unregister(struct blkcg_policy *pol) 
	mutex_unlock(&blkcg_pol_register_mutex);

}

EXPORT_SYMBOL_GPL(blkcg_policy_unregister);



module_param(blkcg_debug_stats, bool, 0644);

MODULE_PARM_DESC(blkcg_debug_stats, "True if you want debug stats, false if not");

include/linux/blk-cgroup.h

+3 −0
Original line number Diff line number Diff line
@@ -148,6 +148,8 @@ typedef void (blkcg_pol_online_pd_fn)(struct blkg_policy_data *pd); 
typedef void (blkcg_pol_offline_pd_fn)(struct blkg_policy_data *pd);

typedef void (blkcg_pol_free_pd_fn)(struct blkg_policy_data *pd);

typedef void (blkcg_pol_reset_pd_stats_fn)(struct blkg_policy_data *pd);

typedef size_t (blkcg_pol_stat_pd_fn)(struct blkg_policy_data *pd, char *buf,

				      size_t size);



struct blkcg_policy {

	int				plid;
@@ -167,6 +169,7 @@ struct blkcg_policy { 
	blkcg_pol_offline_pd_fn		*pd_offline_fn;

	blkcg_pol_free_pd_fn		*pd_free_fn;

	blkcg_pol_reset_pd_stats_fn	*pd_reset_stats_fn;

	blkcg_pol_stat_pd_fn		*pd_stat_fn;

};



extern struct blkcg blkcg_root;