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    SubjectRe: [PATCH 2/3][v2] blkio: Add io controller stats like
    Missed the v2 tag on this patch. Resending. Apologies for the spam.

    On Fri, Apr 2, 2010 at 6:56 PM, Divyesh Shah <dpshah@google.com> wrote:
    > - io_service_time (the actual time in ns taken by the dis to service the IO)
    > - io_wait_time (the time spent waiting in the IO shceduler 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.
    >
    > Signed-off-by: Divyesh Shah<dpshah@google.com>
    > ---
    >
    >  Documentation/cgroups/blkio-controller.txt |   33 +++++
    >  block/blk-cgroup.c                         |  179 +++++++++++++++++++++++++---
    >  block/blk-cgroup.h                         |   41 +++++-
    >  block/cfq-iosched.c                        |    2
    >  4 files changed, 229 insertions(+), 26 deletions(-)
    >
    > diff --git a/Documentation/cgroups/blkio-controller.txt b/Documentation/cgroups/blkio-controller.txt
    > index 630879c..ededdca 100644
    > --- a/Documentation/cgroups/blkio-controller.txt
    > +++ b/Documentation/cgroups/blkio-controller.txt
    > @@ -75,6 +75,9 @@ CONFIG_DEBUG_BLK_CGROUP
    >
    >  Details of cgroup files
    >  =======================
    > +Writing an int to any of the stats files (which excludes weight) will result
    > +in all stats for that cgroup to be erased.
    > +
    >  - blkio.weight
    >        - Specifies per cgroup weight.
    >
    > @@ -92,6 +95,36 @@ 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 spent by the device to service the IOs for this
    > +         cgroup. 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_service_time in ns.
    > +
    > +- blkio.io_wait_time
    > +       - Total amount of time the IO spent waiting in the scheduler queues for
    > +         service. 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
    > diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
    > index 5be3981..cac10b2 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 +57,15 @@ 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 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 +175,119 @@ blkiocg_weight_write(struct cgroup *cgroup, struct cftype *cftype, u64 val)
    >        return 0;
    >  }
    >
    > -#define SHOW_FUNCTION_PER_GROUP(__VAR)                                 \
    > +static int
    > +blkiocg_reset_write(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(int type, dev_t dev, char *str, int chars_left)
    > +{
    > +       snprintf(str, chars_left, "%u:%u", MAJOR(dev), MINOR(dev));
    > +       chars_left -= strlen(str);
    > +       if (chars_left <= 0) {
    > +               printk(KERN_WARNING
    > +                       "Possibly incorrect cgroup stat display format");
    > +               return;
    > +       }
    > +       switch (type) {
    > +       case IO_READ:
    > +               strlcat(str, " Read", chars_left);
    > +               break;
    > +       case IO_WRITE:
    > +               strlcat(str, " Write", chars_left);
    > +               break;
    > +       case IO_SYNC:
    > +               strlcat(str, " Sync", chars_left);
    > +               break;
    > +       case IO_ASYNC:
    > +               strlcat(str, " Async", chars_left);
    > +               break;
    > +       case IO_TYPE_TOTAL:
    > +               strlcat(str, " Total", chars_left);
    > +               break;
    > +       default:
    > +               strlcat(str, " Invalid", chars_left);
    > +       }
    > +}
    > +
    > +typedef uint64_t (get_var) (struct blkio_group *, int);
    > +
    > +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));
    > +       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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