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    SubjectRe: [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@google.com>

    This looks good to me.

    Acked-by: Vivek Goyal <vgoyal@redhat.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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