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Message-ID: <20100407132718.GA14722@redhat.com>
Date: Wed, 7 Apr 2010 09:27:18 -0400
From: Vivek Goyal <vgoyal@...hat.com>
To: Divyesh Shah <dpshah@...gle.com>
Cc: jens.axboe@...cle.com, linux-kernel@...r.kernel.org,
nauman@...gle.com, ctalbott@...gle.com
Subject: Re: [PATCH][v3.1] blkio: Add io controller stats like
On Tue, Apr 06, 2010 at 04:28:06PM -0700, Divyesh Shah wrote:
> - io_service_time (the total time between request dispatch and completion for
> all IOs in the cgroup)
> - io_wait_time (the total time spent waiting by all IOs in this cgroup in the IO
> scheduler queues before getting serviced)
> - io_serviced (number of IOs serviced from this blkio_group)
> - io_service_bytes (Number of bytes served for this cgroup)
>
> These stats are accumulated per operation type helping us to distinguish between
> read and write, and sync and async IO. This patch does not increment any of
> these stats.
>
> Changelog from v3:
> o renamed blkiocg_reset_write to blkiocg_reset_stats
> o more clarification in the documentation on io_service_time and io_wait_time.
>
> Signed-off-by: Divyesh Shah<dpshah@...gle.com>
This looks good to me.
Acked-by: Vivek Goyal <vgoyal@...hat.com>
Vivek
> ---
>
> Documentation/cgroups/blkio-controller.txt | 48 ++++++++
> block/blk-cgroup.c | 166 +++++++++++++++++++++++++---
> block/blk-cgroup.h | 60 ++++++++--
> block/cfq-iosched.c | 3 -
> 4 files changed, 247 insertions(+), 30 deletions(-)
>
> diff --git a/Documentation/cgroups/blkio-controller.txt b/Documentation/cgroups/blkio-controller.txt
> index 630879c..ed04fe9 100644
> --- a/Documentation/cgroups/blkio-controller.txt
> +++ b/Documentation/cgroups/blkio-controller.txt
> @@ -77,7 +77,6 @@ Details of cgroup files
> =======================
> - blkio.weight
> - Specifies per cgroup weight.
> -
> Currently allowed range of weights is from 100 to 1000.
>
> - blkio.time
> @@ -92,6 +91,49 @@ Details of cgroup files
> third field specifies the number of sectors transferred by the
> group to/from the device.
>
> +- blkio.io_service_bytes
> + - Number of bytes transferred to/from the disk by the group. These
> + are further divided by the type of operation - read or write, sync
> + or async. First two fields specify the major and minor number of the
> + device, third field specifies the operation type and the fourth field
> + specifies the number of bytes.
> +
> +- blkio.io_serviced
> + - Number of IOs completed to/from the disk by the group. These
> + are further divided by the type of operation - read or write, sync
> + or async. First two fields specify the major and minor number of the
> + device, third field specifies the operation type and the fourth field
> + specifies the number of IOs.
> +
> +- blkio.io_service_time
> + - Total amount of time between request dispatch and request completion
> + for the IOs done by this cgroup. This is in nanoseconds to make it
> + meaningful for flash devices too. For devices with queue depth of 1,
> + this time represents the actual service time. When queue_depth > 1,
> + that is no longer true as requests may be served out of order. This
> + may cause the service time for a given IO to include the service time
> + of multiple IOs when served out of order which may result in total
> + io_service_time > actual time elapsed. This time is further divided by
> + the type of operation - read or write, sync or async. First two fields
> + specify the major and minor number of the device, third field
> + specifies the operation type and the fourth field specifies the
> + io_service_time in ns.
> +
> +- blkio.io_wait_time
> + - Total amount of time the IOs for this cgroup spent waiting in the
> + scheduler queues for service. This can be greater than the total time
> + elapsed since it is cumulative io_wait_time for all IOs. It is not a
> + measure of total time the cgroup spent waiting but rather a measure of
> + the wait_time for its individual IOs. For devices with queue_depth > 1
> + this metric does not include the time spent waiting for service once
> + the IO is dispatched to the device but till it actually gets serviced
> + (there might be a time lag here due to re-ordering of requests by the
> + device). This is in nanoseconds to make it meaningful for flash
> + devices too. This time is further divided by the type of operation -
> + read or write, sync or async. First two fields specify the major and
> + minor number of the device, third field specifies the operation type
> + and the fourth field specifies the io_wait_time in ns.
> +
> - blkio.dequeue
> - Debugging aid only enabled if CONFIG_DEBUG_CFQ_IOSCHED=y. This
> gives the statistics about how many a times a group was dequeued
> @@ -99,6 +141,10 @@ Details of cgroup files
> and minor number of the device and third field specifies the number
> of times a group was dequeued from a particular device.
>
> +- blkio.reset_stats
> + - Writing an int to this file will result in resetting all the stats
> + for that cgroup.
> +
> CFQ sysfs tunable
> =================
> /sys/block/<disk>/queue/iosched/group_isolation
> diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
> index 5be3981..5849a63 100644
> --- a/block/blk-cgroup.c
> +++ b/block/blk-cgroup.c
> @@ -17,6 +17,8 @@
> #include <linux/err.h>
> #include "blk-cgroup.h"
>
> +#define MAX_KEY_LEN 100
> +
> static DEFINE_SPINLOCK(blkio_list_lock);
> static LIST_HEAD(blkio_list);
>
> @@ -55,12 +57,21 @@ struct blkio_cgroup *cgroup_to_blkio_cgroup(struct cgroup *cgroup)
> }
> EXPORT_SYMBOL_GPL(cgroup_to_blkio_cgroup);
>
> -void blkiocg_update_blkio_group_stats(struct blkio_group *blkg,
> - unsigned long time)
> +void blkio_group_init(struct blkio_group *blkg)
> +{
> + spin_lock_init(&blkg->stats_lock);
> +}
> +EXPORT_SYMBOL_GPL(blkio_group_init);
> +
> +void blkiocg_update_timeslice_used(struct blkio_group *blkg, unsigned long time)
> {
> - blkg->time += time;
> + unsigned long flags;
> +
> + spin_lock_irqsave(&blkg->stats_lock, flags);
> + blkg->stats.time += time;
> + spin_unlock_irqrestore(&blkg->stats_lock, flags);
> }
> -EXPORT_SYMBOL_GPL(blkiocg_update_blkio_group_stats);
> +EXPORT_SYMBOL_GPL(blkiocg_update_timeslice_used);
>
> void blkiocg_add_blkio_group(struct blkio_cgroup *blkcg,
> struct blkio_group *blkg, void *key, dev_t dev)
> @@ -170,13 +181,107 @@ blkiocg_weight_write(struct cgroup *cgroup, struct cftype *cftype, u64 val)
> return 0;
> }
>
> -#define SHOW_FUNCTION_PER_GROUP(__VAR) \
> +static int
> +blkiocg_reset_stats(struct cgroup *cgroup, struct cftype *cftype, u64 val)
> +{
> + struct blkio_cgroup *blkcg;
> + struct blkio_group *blkg;
> + struct hlist_node *n;
> + struct blkio_group_stats *stats;
> +
> + blkcg = cgroup_to_blkio_cgroup(cgroup);
> + spin_lock_irq(&blkcg->lock);
> + hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) {
> + spin_lock(&blkg->stats_lock);
> + stats = &blkg->stats;
> + memset(stats, 0, sizeof(struct blkio_group_stats));
> + spin_unlock(&blkg->stats_lock);
> + }
> + spin_unlock_irq(&blkcg->lock);
> + return 0;
> +}
> +
> +static void blkio_get_key_name(enum stat_sub_type type, dev_t dev, char *str,
> + int chars_left, bool diskname_only)
> +{
> + snprintf(str, chars_left, "%d:%d", MAJOR(dev), MINOR(dev));
> + chars_left -= strlen(str);
> + if (chars_left <= 0) {
> + printk(KERN_WARNING
> + "Possibly incorrect cgroup stat display format");
> + return;
> + }
> + if (diskname_only)
> + return;
> + switch (type) {
> + case BLKIO_STAT_READ:
> + strlcat(str, " Read", chars_left);
> + break;
> + case BLKIO_STAT_WRITE:
> + strlcat(str, " Write", chars_left);
> + break;
> + case BLKIO_STAT_SYNC:
> + strlcat(str, " Sync", chars_left);
> + break;
> + case BLKIO_STAT_ASYNC:
> + strlcat(str, " Async", chars_left);
> + break;
> + case BLKIO_STAT_TOTAL:
> + strlcat(str, " Total", chars_left);
> + break;
> + default:
> + strlcat(str, " Invalid", chars_left);
> + }
> +}
> +
> +static uint64_t blkio_fill_stat(char *str, int chars_left, uint64_t val,
> + struct cgroup_map_cb *cb, dev_t dev)
> +{
> + blkio_get_key_name(0, dev, str, chars_left, true);
> + cb->fill(cb, str, val);
> + return val;
> +}
> +
> +/* This should be called with blkg->stats_lock held */
> +static uint64_t blkio_get_stat(struct blkio_group *blkg,
> + struct cgroup_map_cb *cb, dev_t dev, enum stat_type type)
> +{
> + uint64_t disk_total;
> + char key_str[MAX_KEY_LEN];
> + enum stat_sub_type sub_type;
> +
> + if (type == BLKIO_STAT_TIME)
> + return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
> + blkg->stats.time, cb, dev);
> + if (type == BLKIO_STAT_SECTORS)
> + return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
> + blkg->stats.sectors, cb, dev);
> +#ifdef CONFIG_DEBUG_BLK_CGROUP
> + if (type == BLKIO_STAT_DEQUEUE)
> + return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
> + blkg->stats.dequeue, cb, dev);
> +#endif
> +
> + for (sub_type = BLKIO_STAT_READ; sub_type < BLKIO_STAT_TOTAL;
> + sub_type++) {
> + blkio_get_key_name(sub_type, dev, key_str, MAX_KEY_LEN, false);
> + cb->fill(cb, key_str, blkg->stats.stat_arr[type][sub_type]);
> + }
> + disk_total = blkg->stats.stat_arr[type][BLKIO_STAT_READ] +
> + blkg->stats.stat_arr[type][BLKIO_STAT_WRITE];
> + blkio_get_key_name(BLKIO_STAT_TOTAL, dev, key_str, MAX_KEY_LEN, false);
> + cb->fill(cb, key_str, disk_total);
> + return disk_total;
> +}
> +
> +#define SHOW_FUNCTION_PER_GROUP(__VAR, type, 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 +289,28 @@ 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 += blkio_get_stat(blkg, cb, \
> + blkg->dev, type); \
> + 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_STAT_TIME, 0);
> +SHOW_FUNCTION_PER_GROUP(sectors, BLKIO_STAT_SECTORS, 0);
> +SHOW_FUNCTION_PER_GROUP(io_service_bytes, BLKIO_STAT_SERVICE_BYTES, 1);
> +SHOW_FUNCTION_PER_GROUP(io_serviced, BLKIO_STAT_SERVICED, 1);
> +SHOW_FUNCTION_PER_GROUP(io_service_time, BLKIO_STAT_SERVICE_TIME, 1);
> +SHOW_FUNCTION_PER_GROUP(io_wait_time, BLKIO_STAT_WAIT_TIME, 1);
> #ifdef CONFIG_DEBUG_BLK_CGROUP
> -SHOW_FUNCTION_PER_GROUP(dequeue);
> +SHOW_FUNCTION_PER_GROUP(dequeue, BLKIO_STAT_DEQUEUE, 0);
> #endif
> #undef SHOW_FUNCTION_PER_GROUP
>
> @@ -204,7 +318,7 @@ 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 +331,36 @@ struct cftype blkio_files[] = {
> },
> {
> .name = "time",
> - .read_seq_string = blkiocg_time_read,
> + .read_map = blkiocg_time_read,
> },
> {
> .name = "sectors",
> - .read_seq_string = blkiocg_sectors_read,
> + .read_map = blkiocg_sectors_read,
> + },
> + {
> + .name = "io_service_bytes",
> + .read_map = blkiocg_io_service_bytes_read,
> + },
> + {
> + .name = "io_serviced",
> + .read_map = blkiocg_io_serviced_read,
> + },
> + {
> + .name = "io_service_time",
> + .read_map = blkiocg_io_service_time_read,
> + },
> + {
> + .name = "io_wait_time",
> + .read_map = blkiocg_io_wait_time_read,
> + },
> + {
> + .name = "reset_stats",
> + .write_u64 = blkiocg_reset_stats,
> },
> #ifdef CONFIG_DEBUG_BLK_CGROUP
> {
> .name = "dequeue",
> - .read_seq_string = blkiocg_dequeue_read,
> + .read_map = blkiocg_dequeue_read,
> },
> #endif
> };
> diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h
> index fe44517..a4bc4bb 100644
> --- a/block/blk-cgroup.h
> +++ b/block/blk-cgroup.h
> @@ -23,6 +23,33 @@ extern struct cgroup_subsys blkio_subsys;
> #define blkio_subsys_id blkio_subsys.subsys_id
> #endif
>
> +enum stat_type {
> + /* Total time spent (in ns) between request dispatch to the driver and
> + * request completion for IOs doen by this cgroup. This may not be
> + * accurate when NCQ is turned on. */
> + BLKIO_STAT_SERVICE_TIME = 0,
> + /* Total bytes transferred */
> + BLKIO_STAT_SERVICE_BYTES,
> + /* Total IOs serviced, post merge */
> + BLKIO_STAT_SERVICED,
> + /* Total time spent waiting in scheduler queue in ns */
> + BLKIO_STAT_WAIT_TIME,
> + /* All the single valued stats go below this */
> + BLKIO_STAT_TIME,
> + BLKIO_STAT_SECTORS,
> +#ifdef CONFIG_DEBUG_BLK_CGROUP
> + BLKIO_STAT_DEQUEUE
> +#endif
> +};
> +
> +enum stat_sub_type {
> + BLKIO_STAT_READ = 0,
> + BLKIO_STAT_WRITE,
> + BLKIO_STAT_SYNC,
> + BLKIO_STAT_ASYNC,
> + BLKIO_STAT_TOTAL
> +};
> +
> struct blkio_cgroup {
> struct cgroup_subsys_state css;
> unsigned int weight;
> @@ -30,6 +57,17 @@ 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;
> + uint64_t stat_arr[BLKIO_STAT_WAIT_TIME + 1][BLKIO_STAT_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 +76,13 @@ 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);
> @@ -105,24 +141,24 @@ 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 blkio_group_init(struct blkio_group *blkg);
> +void blkiocg_update_timeslice_used(struct blkio_group *blkg,
> + unsigned long time);
> #else
> struct cgroup;
> static inline struct blkio_cgroup *
> cgroup_to_blkio_cgroup(struct cgroup *cgroup) { return NULL; }
>
> +static inline void blkio_group_init(struct blkio_group *blkg) {}
> static inline void blkiocg_add_blkio_group(struct blkio_cgroup *blkcg,
> - struct blkio_group *blkg, void *key, dev_t dev)
> -{
> -}
> + struct blkio_group *blkg, void *key, dev_t dev) {}
>
> static inline int
> 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..cf11548 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
> @@ -954,6 +954,7 @@ cfq_find_alloc_cfqg(struct cfq_data *cfqd, struct cgroup *cgroup, int create)
> for_each_cfqg_st(cfqg, i, j, st)
> *st = CFQ_RB_ROOT;
> RB_CLEAR_NODE(&cfqg->rb_node);
> + blkio_group_init(&cfqg->blkg);
>
> /*
> * Take the initial reference that will be released on destroy
--
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