Re: [PATCH 2/3][v2] blkio: Add io controller stats like

[Vivek Goyal]

On Fri, Apr 02, 2010 at 06:56:35PM -0700, Divyesh Shah wrote:

[..]
> +static uint64_t blkio_get_typed_stat(struct blkio_group *blkg,
> +		struct cgroup_map_cb *cb, get_var *getvar, dev_t dev)
> +{
> +	uint64_t disk_total;
> +	char key_str[MAX_KEY_LEN];
> +	int type;
> +
> +	for (type = 0; type < IO_TYPE_TOTAL; type++) {
> +		blkio_get_key_name(type, dev, key_str, MAX_KEY_LEN);
> +		cb->fill(cb, key_str, getvar(blkg, type));
> +	}
> +	disk_total = getvar(blkg, IO_READ) + getvar(blkg, IO_WRITE);
> +	blkio_get_key_name(IO_TYPE_TOTAL, dev, key_str, MAX_KEY_LEN);
> +	cb->fill(cb, key_str, disk_total);
> +	return disk_total;
> +}
> +
> +static uint64_t blkio_get_stat(struct blkio_group *blkg,
> +		struct cgroup_map_cb *cb, get_var *getvar, dev_t dev)
> +{
> +	uint64_t var = getvar(blkg, 0);
> +	char str[10];
> +
> +	snprintf(str, 10, "%u:%u", MAJOR(dev), MINOR(dev));

What is the significance of limiting major:minor string to 10 characters?
I see BDEVT_SIZE being used in genhd.c. But it looks like it is valid
only if we printing numbers in hex.

In genhd.c:diskstats_show(), we seem to be using %4d and %7d for major
minor numbers. In extended minor allocation scheme, we seem to be having
20 bits for minor numbers, so 7 decimal places for representing max minor
number will make sense. Not sure about major number though.

So it might be safe to just to follow diskstats_show convention and at
least keep the buffer size as 12 (4:7).

Vivek

> +	cb->fill(cb, str, var);
> +	return var;
> +}
> +
> +#define GET_STAT_INDEXED(__VAR)						\
> +uint64_t blkio_get_##__VAR##_stat(struct blkio_group *blkg, int type)	\
> +{									\
> +	return blkg->stats.__VAR[type];					\
> +}									\
> +
> +GET_STAT_INDEXED(io_service_bytes);
> +GET_STAT_INDEXED(io_serviced);
> +GET_STAT_INDEXED(io_service_time);
> +GET_STAT_INDEXED(io_wait_time);
> +#undef GET_STAT_INDEXED
> +
> +#define GET_STAT(__VAR)							\
> +uint64_t blkio_get_##__VAR##_stat(struct blkio_group *blkg, int dummy)	\
> +{									\
> +	return blkg->stats.__VAR;					\
> +}
> +
> +GET_STAT(time);
> +GET_STAT(sectors);
> +#ifdef CONFIG_DEBUG_BLK_CGROUP
> +GET_STAT(dequeue);
> +#endif
> +#undef GET_STAT
> +
> +#define SHOW_FUNCTION_PER_GROUP(__VAR, get_stats, getvar, show_total)	\
>  static int blkiocg_##__VAR##_read(struct cgroup *cgroup,		\
> -			struct cftype *cftype, struct seq_file *m)	\
> +		struct cftype *cftype, struct cgroup_map_cb *cb)	\
>  {									\
>  	struct blkio_cgroup *blkcg;					\
>  	struct blkio_group *blkg;					\
>  	struct hlist_node *n;						\
> +	uint64_t cgroup_total = 0;					\
>  									\
>  	if (!cgroup_lock_live_group(cgroup))				\
>  		return -ENODEV;						\
> @@ -184,19 +295,32 @@ static int blkiocg_##__VAR##_read(struct cgroup *cgroup,		\
>  	blkcg = cgroup_to_blkio_cgroup(cgroup);				\
>  	rcu_read_lock();						\
>  	hlist_for_each_entry_rcu(blkg, n, &blkcg->blkg_list, blkcg_node) {\
> -		if (blkg->dev)						\
> -			seq_printf(m, "%u:%u %lu\n", MAJOR(blkg->dev),	\
> -				 MINOR(blkg->dev), blkg->__VAR);	\
> +		if (blkg->dev) {					\
> +			spin_lock_irq(&blkg->stats_lock);		\
> +			cgroup_total += get_stats(blkg, cb, getvar,	\
> +						blkg->dev);		\
> +			spin_unlock_irq(&blkg->stats_lock);		\
> +		}							\
>  	}								\
> +	if (show_total)							\
> +		cb->fill(cb, "Total", cgroup_total);			\
>  	rcu_read_unlock();						\
>  	cgroup_unlock();						\
>  	return 0;							\
>  }
>  
> -SHOW_FUNCTION_PER_GROUP(time);
> -SHOW_FUNCTION_PER_GROUP(sectors);
> +SHOW_FUNCTION_PER_GROUP(time, blkio_get_stat, blkio_get_time_stat, 0);
> +SHOW_FUNCTION_PER_GROUP(sectors, blkio_get_stat, blkio_get_sectors_stat, 0);
> +SHOW_FUNCTION_PER_GROUP(io_service_bytes, blkio_get_typed_stat,
> +			blkio_get_io_service_bytes_stat, 1);
> +SHOW_FUNCTION_PER_GROUP(io_serviced, blkio_get_typed_stat,
> +			blkio_get_io_serviced_stat, 1);
> +SHOW_FUNCTION_PER_GROUP(io_service_time, blkio_get_typed_stat,
> +			blkio_get_io_service_time_stat, 1);
> +SHOW_FUNCTION_PER_GROUP(io_wait_time, blkio_get_typed_stat,
> +			blkio_get_io_wait_time_stat, 1);
>  #ifdef CONFIG_DEBUG_BLK_CGROUP
> -SHOW_FUNCTION_PER_GROUP(dequeue);
> +SHOW_FUNCTION_PER_GROUP(dequeue, blkio_get_stat, blkio_get_dequeue_stat, 0);
>  #endif
>  #undef SHOW_FUNCTION_PER_GROUP
>  
> @@ -204,7 +328,7 @@ SHOW_FUNCTION_PER_GROUP(dequeue);
>  void blkiocg_update_blkio_group_dequeue_stats(struct blkio_group *blkg,
>  			unsigned long dequeue)
>  {
> -	blkg->dequeue += dequeue;
> +	blkg->stats.dequeue += dequeue;
>  }
>  EXPORT_SYMBOL_GPL(blkiocg_update_blkio_group_dequeue_stats);
>  #endif
> @@ -217,16 +341,39 @@ struct cftype blkio_files[] = {
>  	},
>  	{
>  		.name = "time",
> -		.read_seq_string = blkiocg_time_read,
> +		.read_map = blkiocg_time_read,
> +		.write_u64 = blkiocg_reset_write,
>  	},
>  	{
>  		.name = "sectors",
> -		.read_seq_string = blkiocg_sectors_read,
> +		.read_map = blkiocg_sectors_read,
> +		.write_u64 = blkiocg_reset_write,
> +	},
> +	{
> +		.name = "io_service_bytes",
> +		.read_map = blkiocg_io_service_bytes_read,
> +		.write_u64 = blkiocg_reset_write,
> +	},
> +	{
> +		.name = "io_serviced",
> +		.read_map = blkiocg_io_serviced_read,
> +		.write_u64 = blkiocg_reset_write,
> +	},
> +	{
> +		.name = "io_service_time",
> +		.read_map = blkiocg_io_service_time_read,
> +		.write_u64 = blkiocg_reset_write,
> +	},
> +	{
> +		.name = "io_wait_time",
> +		.read_map = blkiocg_io_wait_time_read,
> +		.write_u64 = blkiocg_reset_write,
>  	},
>  #ifdef CONFIG_DEBUG_BLK_CGROUP
>         {
>  		.name = "dequeue",
> -		.read_seq_string = blkiocg_dequeue_read,
> +		.read_map = blkiocg_dequeue_read,
> +		.write_u64 = blkiocg_reset_write,
>         },
>  #endif
>  };
> diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h
> index fe44517..e8600b0 100644
> --- a/block/blk-cgroup.h
> +++ b/block/blk-cgroup.h
> @@ -23,6 +23,14 @@ extern struct cgroup_subsys blkio_subsys;
>  #define blkio_subsys_id blkio_subsys.subsys_id
>  #endif
>  
> +enum io_type {
> +	IO_READ = 0,
> +	IO_WRITE,
> +	IO_SYNC,
> +	IO_ASYNC,
> +	IO_TYPE_TOTAL
> +};
> +
>  struct blkio_cgroup {
>  	struct cgroup_subsys_state css;
>  	unsigned int weight;
> @@ -30,6 +38,23 @@ struct blkio_cgroup {
>  	struct hlist_head blkg_list;
>  };
>  
> +struct blkio_group_stats {
> +	/* total disk time and nr sectors dispatched by this group */
> +	uint64_t time;
> +	uint64_t sectors;
> +	/* Total disk time used by IOs in ns */
> +	uint64_t io_service_time[IO_TYPE_TOTAL];
> +	uint64_t io_service_bytes[IO_TYPE_TOTAL]; /* Total bytes transferred */
> +	/* Total IOs serviced, post merge */
> +	uint64_t io_serviced[IO_TYPE_TOTAL];
> +	/* Total time spent waiting in scheduler queue in ns */
> +	uint64_t io_wait_time[IO_TYPE_TOTAL];
> +#ifdef CONFIG_DEBUG_BLK_CGROUP
> +	/* How many times this group has been removed from service tree */
> +	unsigned long dequeue;
> +#endif
> +};
> +
>  struct blkio_group {
>  	/* An rcu protected unique identifier for the group */
>  	void *key;
> @@ -38,15 +63,13 @@ struct blkio_group {
>  #ifdef CONFIG_DEBUG_BLK_CGROUP
>  	/* Store cgroup path */
>  	char path[128];
> -	/* How many times this group has been removed from service tree */
> -	unsigned long dequeue;
>  #endif
>  	/* The device MKDEV(major, minor), this group has been created for */
> -	dev_t   dev;
> +	dev_t dev;
>  
> -	/* total disk time and nr sectors dispatched by this group */
> -	unsigned long time;
> -	unsigned long sectors;
> +	/* Need to serialize the stats in the case of reset/update */
> +	spinlock_t stats_lock;
> +	struct blkio_group_stats stats;
>  };
>  
>  typedef void (blkio_unlink_group_fn) (void *key, struct blkio_group *blkg);
> @@ -105,8 +128,8 @@ extern void blkiocg_add_blkio_group(struct blkio_cgroup *blkcg,
>  extern int blkiocg_del_blkio_group(struct blkio_group *blkg);
>  extern struct blkio_group *blkiocg_lookup_group(struct blkio_cgroup *blkcg,
>  						void *key);
> -void blkiocg_update_blkio_group_stats(struct blkio_group *blkg,
> -						unsigned long time);
> +void blkiocg_update_timeslice_used(struct blkio_group *blkg,
> +					unsigned long time);
>  #else
>  struct cgroup;
>  static inline struct blkio_cgroup *
> @@ -122,7 +145,7 @@ blkiocg_del_blkio_group(struct blkio_group *blkg) { return 0; }
>  
>  static inline struct blkio_group *
>  blkiocg_lookup_group(struct blkio_cgroup *blkcg, void *key) { return NULL; }
> -static inline void blkiocg_update_blkio_group_stats(struct blkio_group *blkg,
> +static inline void blkiocg_update_timeslice_used(struct blkio_group *blkg,
>  						unsigned long time) {}
>  #endif
>  #endif /* _BLK_CGROUP_H */
> diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
> index c18e348..d91df9f 100644
> --- a/block/cfq-iosched.c
> +++ b/block/cfq-iosched.c
> @@ -914,7 +914,7 @@ static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg,
>  
>  	cfq_log_cfqg(cfqd, cfqg, "served: vt=%llu min_vt=%llu", cfqg->vdisktime,
>  					st->min_vdisktime);
> -	blkiocg_update_blkio_group_stats(&cfqg->blkg, used_sl);
> +	blkiocg_update_timeslice_used(&cfqg->blkg, used_sl);
>  }
>  
>  #ifdef CONFIG_CFQ_GROUP_IOSCHED
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