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    Subject[PATCH 18/19] io-controller: Debug hierarchical IO scheduling
    Date
    o Littile debugging aid for hierarchical IO scheduling.

    o Enabled under CONFIG_DEBUG_GROUP_IOSCHED

    o Currently it outputs more debug messages in blktrace output which helps
    a great deal in debugging in hierarchical setup. It also creates additional
    cgroup interfaces io.disk_queue and io.disk_dequeue to output some more
    debugging data.

    Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
    ---
    block/Kconfig.iosched | 10 ++-
    block/as-iosched.c | 50 ++++++---
    block/elevator-fq.c | 285 ++++++++++++++++++++++++++++++++++++++++++++++++-
    block/elevator-fq.h | 26 +++++
    4 files changed, 347 insertions(+), 24 deletions(-)

    diff --git a/block/Kconfig.iosched b/block/Kconfig.iosched
    index 0677099..79f188c 100644
    --- a/block/Kconfig.iosched
    +++ b/block/Kconfig.iosched
    @@ -140,6 +140,14 @@ config TRACK_ASYNC_CONTEXT
    request, original owner of the bio is decided by using io tracking
    patches otherwise we continue to attribute the request to the
    submitting thread.
    -endmenu

    +config DEBUG_GROUP_IOSCHED
    + bool "Debug Hierarchical Scheduling support"
    + depends on CGROUPS && GROUP_IOSCHED
    + default n
    + ---help---
    + Enable some debugging hooks for hierarchical scheduling support.
    + Currently it just outputs more information in blktrace output.
    +
    +endmenu
    endif
    diff --git a/block/as-iosched.c b/block/as-iosched.c
    index b0c66e4..735d055 100644
    --- a/block/as-iosched.c
    +++ b/block/as-iosched.c
    @@ -78,6 +78,7 @@ enum anticipation_status {
    };

    struct as_queue {
    + struct io_queue *ioq;
    /*
    * requests (as_rq s) are present on both sort_list and fifo_list
    */
    @@ -162,6 +163,17 @@ enum arq_state {
    #define RQ_STATE(rq) ((enum arq_state)(rq)->elevator_private2)
    #define RQ_SET_STATE(rq, state) ((rq)->elevator_private2 = (void *) state)

    +#ifdef CONFIG_DEBUG_GROUP_IOSCHED
    +#define as_log_asq(ad, asq, fmt, args...) \
    +{ \
    + blk_add_trace_msg((ad)->q, "as %s " fmt, \
    + ioq_to_io_group((asq)->ioq)->path, ##args); \
    +}
    +#else
    +#define as_log_asq(ad, asq, fmt, args...) \
    + blk_add_trace_msg((ad)->q, "as " fmt, ##args)
    +#endif
    +
    #define as_log(ad, fmt, args...) \
    blk_add_trace_msg((ad)->q, "as " fmt, ##args)

    @@ -225,7 +237,7 @@ static void as_save_batch_context(struct as_data *ad, struct as_queue *asq)
    }

    out:
    - as_log(ad, "save batch: dir=%c time_left=%d changed_batch=%d"
    + as_log_asq(ad, asq, "save batch: dir=%c time_left=%d changed_batch=%d"
    " new_batch=%d, antic_status=%d",
    ad->batch_data_dir ? 'R' : 'W',
    asq->current_batch_time_left,
    @@ -247,8 +259,8 @@ static void as_restore_batch_context(struct as_data *ad, struct as_queue *asq)
    asq->current_batch_time_left;
    /* restore asq batch_data_dir info */
    ad->batch_data_dir = asq->saved_batch_data_dir;
    - as_log(ad, "restore batch: dir=%c time=%d reads_q=%d writes_q=%d"
    - " ad->antic_status=%d",
    + as_log_asq(ad, asq, "restore batch: dir=%c time=%d reads_q=%d"
    + " writes_q=%d ad->antic_status=%d",
    ad->batch_data_dir ? 'R' : 'W',
    asq->current_batch_time_left,
    asq->nr_queued[1], asq->nr_queued[0],
    @@ -277,8 +289,8 @@ static int as_expire_ioq(struct request_queue *q, void *sched_queue,
    int status = ad->antic_status;
    struct as_queue *asq = sched_queue;

    - as_log(ad, "as_expire_ioq slice_expired=%d, force=%d", slice_expired,
    - force);
    + as_log_asq(ad, asq, "as_expire_ioq slice_expired=%d, force=%d",
    + slice_expired, force);

    /* Forced expiry. We don't have a choice */
    if (force) {
    @@ -1019,9 +1031,10 @@ static void update_write_batch(struct as_data *ad, struct request *rq)
    if (write_time < 0)
    write_time = 0;

    - as_log(ad, "upd write: write_time=%d batch=%d write_batch_idled=%d"
    - " current_write_count=%d", write_time, batch,
    - asq->write_batch_idled, asq->current_write_count);
    + as_log_asq(ad, asq, "upd write: write_time=%d batch=%d"
    + " write_batch_idled=%d current_write_count=%d",
    + write_time, batch, asq->write_batch_idled,
    + asq->current_write_count);

    if (write_time > batch && !asq->write_batch_idled) {
    if (write_time > batch * 3)
    @@ -1038,7 +1051,7 @@ static void update_write_batch(struct as_data *ad, struct request *rq)
    if (asq->write_batch_count < 1)
    asq->write_batch_count = 1;

    - as_log(ad, "upd write count=%d", asq->write_batch_count);
    + as_log_asq(ad, asq, "upd write count=%d", asq->write_batch_count);
    }

    /*
    @@ -1057,7 +1070,7 @@ static void as_completed_request(struct request_queue *q, struct request *rq)
    goto out;
    }

    - as_log(ad, "complete: reads_q=%d writes_q=%d changed_batch=%d"
    + as_log_asq(ad, asq, "complete: reads_q=%d writes_q=%d changed_batch=%d"
    " new_batch=%d switch_queue=%d, dir=%c",
    asq->nr_queued[1], asq->nr_queued[0], ad->changed_batch,
    ad->new_batch, ad->switch_queue,
    @@ -1251,7 +1264,7 @@ static void as_move_to_dispatch(struct as_data *ad, struct request *rq)
    if (RQ_IOC(rq) && RQ_IOC(rq)->aic)
    atomic_inc(&RQ_IOC(rq)->aic->nr_dispatched);
    ad->nr_dispatched++;
    - as_log(ad, "dispatch req dir=%c nr_dispatched = %d",
    + as_log_asq(ad, asq, "dispatch req dir=%c nr_dispatched = %d",
    data_dir ? 'R' : 'W', ad->nr_dispatched);
    }

    @@ -1300,7 +1313,7 @@ static int as_dispatch_request(struct request_queue *q, int force)
    }
    asq->last_check_fifo[BLK_RW_ASYNC] = jiffies;

    - as_log(ad, "forced dispatch");
    + as_log_asq(ad, asq, "forced dispatch");
    return dispatched;
    }

    @@ -1314,7 +1327,7 @@ static int as_dispatch_request(struct request_queue *q, int force)
    || ad->antic_status == ANTIC_WAIT_REQ
    || ad->antic_status == ANTIC_WAIT_NEXT
    || ad->changed_batch) {
    - as_log(ad, "no dispatch. read_q=%d, writes_q=%d"
    + as_log_asq(ad, asq, "no dispatch. read_q=%d, writes_q=%d"
    " ad->antic_status=%d, changed_batch=%d,"
    " switch_queue=%d new_batch=%d", asq->nr_queued[1],
    asq->nr_queued[0], ad->antic_status, ad->changed_batch,
    @@ -1333,7 +1346,7 @@ static int as_dispatch_request(struct request_queue *q, int force)
    goto fifo_expired;

    if (as_can_anticipate(ad, rq)) {
    - as_log(ad, "can_anticipate = 1");
    + as_log_asq(ad, asq, "can_anticipate = 1");
    as_antic_waitreq(ad);
    return 0;
    }
    @@ -1353,7 +1366,7 @@ static int as_dispatch_request(struct request_queue *q, int force)
    * data direction (read / write)
    */

    - as_log(ad, "select a fresh batch and request");
    + as_log_asq(ad, asq, "select a fresh batch and request");

    if (reads) {
    BUG_ON(RB_EMPTY_ROOT(&asq->sort_list[BLK_RW_SYNC]));
    @@ -1369,7 +1382,7 @@ static int as_dispatch_request(struct request_queue *q, int force)
    ad->changed_batch = 1;
    }
    ad->batch_data_dir = BLK_RW_SYNC;
    - as_log(ad, "new batch dir is sync");
    + as_log_asq(ad, asq, "new batch dir is sync");
    rq = rq_entry_fifo(asq->fifo_list[BLK_RW_SYNC].next);
    asq->last_check_fifo[ad->batch_data_dir] = jiffies;
    goto dispatch_request;
    @@ -1394,7 +1407,7 @@ dispatch_writes:
    ad->new_batch = 0;
    }
    ad->batch_data_dir = BLK_RW_ASYNC;
    - as_log(ad, "new batch dir is async");
    + as_log_asq(ad, asq, "new batch dir is async");
    asq->current_write_count = asq->write_batch_count;
    asq->write_batch_idled = 0;
    rq = rq_entry_fifo(asq->fifo_list[BLK_RW_ASYNC].next);
    @@ -1457,7 +1470,7 @@ static void as_add_request(struct request_queue *q, struct request *rq)
    rq->elevator_private = as_get_io_context(q->node);

    asq->nr_queued[data_dir]++;
    - as_log(ad, "add a %c request read_q=%d write_q=%d",
    + as_log_asq(ad, asq, "add a %c request read_q=%d write_q=%d",
    data_dir ? 'R' : 'W', asq->nr_queued[1],
    asq->nr_queued[0]);

    @@ -1616,6 +1629,7 @@ static void *as_alloc_as_queue(struct request_queue *q,

    if (asq->write_batch_count < 2)
    asq->write_batch_count = 2;
    + asq->ioq = ioq;
    out:
    return asq;
    }
    diff --git a/block/elevator-fq.c b/block/elevator-fq.c
    index 207664d..207bdf1 100644
    --- a/block/elevator-fq.c
    +++ b/block/elevator-fq.c
    @@ -117,6 +117,126 @@ static inline int iog_deleting(struct io_group *iog)
    return iog->deleting;
    }

    +static inline struct io_group *io_entity_to_iog(struct io_entity *entity)
    +{
    + struct io_group *iog = NULL;
    +
    + BUG_ON(entity == NULL);
    + if (entity->my_sched_data != NULL)
    + iog = container_of(entity, struct io_group, entity);
    + return iog;
    +}
    +
    +/* Returns parent group of io group */
    +static inline struct io_group *iog_parent(struct io_group *iog)
    +{
    + struct io_group *piog;
    +
    + if (!iog->entity.sched_data)
    + return NULL;
    +
    + /*
    + * Not following entity->parent pointer as for top level groups
    + * this pointer is NULL.
    + */
    + piog = container_of(iog->entity.sched_data, struct io_group,
    + sched_data);
    + return piog;
    +}
    +
    +#ifdef CONFIG_DEBUG_GROUP_IOSCHED
    +static void io_group_path(struct io_group *iog, char *buf, int buflen)
    +{
    + unsigned short id = iog->iocg_id;
    + struct cgroup_subsys_state *css;
    +
    + rcu_read_lock();
    +
    + if (!id)
    + goto out;
    +
    + css = css_lookup(&io_subsys, id);
    + if (!css)
    + goto out;
    +
    + if (!css_tryget(css))
    + goto out;
    +
    + cgroup_path(css->cgroup, buf, buflen);
    +
    + css_put(css);
    +
    + rcu_read_unlock();
    + return;
    +out:
    + rcu_read_unlock();
    + buf[0] = '\0';
    + return;
    +}
    +
    +/*
    + * An entity has been freshly added to active tree. Either it came from
    + * idle tree or it was not on any of the trees. Do the accounting.
    + */
    +static inline void bfq_account_for_entity_addition(struct io_entity *entity)
    +{
    + struct io_group *iog = io_entity_to_iog(entity);
    +
    + if (iog) {
    + struct elv_fq_data *efqd;
    + char path[128];
    +
    + /*
    + * Keep track of how many times a group has been removed
    + * from active tree because it did not have any active
    + * backlogged ioq under it
    + */
    + iog->queue++;
    + iog->queue_start = jiffies;
    +
    + /* Log group addition event */
    + rcu_read_lock();
    + efqd = rcu_dereference(iog->key);
    + if (efqd) {
    + io_group_path(iog, path, sizeof(path));
    + elv_log(efqd, "add group=%s weight=%ld", path,
    + iog->entity.weight);
    + }
    + rcu_read_unlock();
    + }
    +}
    +
    +/*
    + * An entity got removed from active tree and either went to idle tree or
    + * not is on any of the tree. Do the accouting
    + */
    +static inline void bfq_account_for_entity_deletion(struct io_entity *entity)
    +{
    + struct io_group *iog = io_entity_to_iog(entity);
    +
    + if (iog) {
    + struct elv_fq_data *efqd;
    + char path[128];
    +
    + iog->dequeue++;
    + /* Keep a track of how long group was on active tree */
    + iog->queue_duration += jiffies_to_msecs(jiffies -
    + iog->queue_start);
    + iog->queue_start = 0;
    +
    + /* Log group deletion event */
    + rcu_read_lock();
    + efqd = rcu_dereference(iog->key);
    + if (efqd) {
    + io_group_path(iog, path, sizeof(path));
    + elv_log(efqd, "del group=%s weight=%ld", path,
    + iog->entity.weight);
    + }
    + rcu_read_unlock();
    + }
    +}
    +#endif
    +
    #else /* GROUP_IOSCHED */
    #define for_each_entity(entity) \
    for (; entity != NULL; entity = NULL)
    @@ -139,6 +259,12 @@ static inline int iog_deleting(struct io_group *iog)
    /* In flat mode, root cgroup can't be deleted. */
    return 0;
    }
    +
    +static inline struct io_group *io_entity_to_iog(struct io_entity *entity)
    +{
    + return NULL;
    +}
    +
    #endif

    /*
    @@ -572,6 +698,7 @@ static void __bfq_activate_entity(struct io_entity *entity, int add_front)
    {
    struct io_sched_data *sd = entity->sched_data;
    struct io_service_tree *st = io_entity_service_tree(entity);
    + int newly_added = 0;

    if (entity == sd->active_entity) {
    BUG_ON(entity->tree != NULL);
    @@ -598,6 +725,7 @@ static void __bfq_activate_entity(struct io_entity *entity, int add_front)
    bfq_idle_extract(st, entity);
    entity->start = bfq_gt(st->vtime, entity->finish) ?
    st->vtime : entity->finish;
    + newly_added = 1;
    } else {
    /*
    * The finish time of the entity may be invalid, and
    @@ -610,6 +738,7 @@ static void __bfq_activate_entity(struct io_entity *entity, int add_front)

    BUG_ON(entity->on_st);
    entity->on_st = 1;
    + newly_added = 1;
    }

    st = __bfq_entity_update_prio(st, entity);
    @@ -647,6 +776,10 @@ static void __bfq_activate_entity(struct io_entity *entity, int add_front)
    bfq_calc_finish(entity, entity->budget);
    }
    bfq_active_insert(st, entity);
    +#ifdef CONFIG_DEBUG_GROUP_IOSCHED
    + if (newly_added)
    + bfq_account_for_entity_addition(entity);
    +#endif
    }

    /**
    @@ -717,6 +850,9 @@ int __bfq_deactivate_entity(struct io_entity *entity, int requeue)
    BUG_ON(sd->active_entity == entity);
    BUG_ON(sd->next_active == entity);

    +#ifdef CONFIG_DEBUG_GROUP_IOSCHED
    + bfq_account_for_entity_deletion(entity);
    +#endif
    return ret;
    }

    @@ -1209,6 +1345,67 @@ static int io_cgroup_disk_sectors_read(struct cgroup *cgroup,
    return 0;
    }

    +#ifdef CONFIG_DEBUG_GROUP_IOSCHED
    +static int io_cgroup_disk_queue_read(struct cgroup *cgroup,
    + struct cftype *cftype, struct seq_file *m)
    +{
    + struct io_cgroup *iocg = NULL;
    + struct io_group *iog = NULL;
    + struct hlist_node *n;
    +
    + if (!cgroup_lock_live_group(cgroup))
    + return -ENODEV;
    +
    + iocg = cgroup_to_io_cgroup(cgroup);
    + spin_lock_irq(&iocg->lock);
    + /* Loop through all the io groups and print statistics */
    + hlist_for_each_entry_rcu(iog, n, &iocg->group_data, group_node) {
    + /*
    + * There might be groups which are not functional and
    + * waiting to be reclaimed upon cgoup deletion.
    + */
    + if (iog->key) {
    + seq_printf(m, "%u %u %lu %lu\n", MAJOR(iog->dev),
    + MINOR(iog->dev), iog->queue,
    + iog->queue_duration);
    + }
    + }
    + spin_unlock_irq(&iocg->lock);
    + cgroup_unlock();
    +
    + return 0;
    +}
    +
    +static int io_cgroup_disk_dequeue_read(struct cgroup *cgroup,
    + struct cftype *cftype, struct seq_file *m)
    +{
    + struct io_cgroup *iocg = NULL;
    + struct io_group *iog = NULL;
    + struct hlist_node *n;
    +
    + if (!cgroup_lock_live_group(cgroup))
    + return -ENODEV;
    +
    + iocg = cgroup_to_io_cgroup(cgroup);
    + spin_lock_irq(&iocg->lock);
    + /* Loop through all the io groups and print statistics */
    + hlist_for_each_entry_rcu(iog, n, &iocg->group_data, group_node) {
    + /*
    + * There might be groups which are not functional and
    + * waiting to be reclaimed upon cgoup deletion.
    + */
    + if (iog->key) {
    + seq_printf(m, "%u %u %lu\n", MAJOR(iog->dev),
    + MINOR(iog->dev), iog->dequeue);
    + }
    + }
    + spin_unlock_irq(&iocg->lock);
    + cgroup_unlock();
    +
    + return 0;
    +}
    +#endif
    +
    /**
    * bfq_group_chain_alloc - allocate a chain of groups.
    * @bfqd: queue descriptor.
    @@ -1263,7 +1460,9 @@ struct io_group *io_group_chain_alloc(struct request_queue *q, void *key,
    }

    blk_init_request_list(&iog->rl);
    -
    +#ifdef CONFIG_DEBUG_GROUP_IOSCHED
    + io_group_path(iog, iog->path, sizeof(iog->path));
    +#endif
    if (leaf == NULL) {
    leaf = iog;
    prev = leaf;
    @@ -1766,6 +1965,16 @@ struct cftype bfqio_files[] = {
    .name = "disk_sectors",
    .read_seq_string = io_cgroup_disk_sectors_read,
    },
    +#ifdef CONFIG_DEBUG_GROUP_IOSCHED
    + {
    + .name = "disk_queue",
    + .read_seq_string = io_cgroup_disk_queue_read,
    + },
    + {
    + .name = "disk_dequeue",
    + .read_seq_string = io_cgroup_disk_dequeue_read,
    + },
    +#endif
    };

    int iocg_populate(struct cgroup_subsys *subsys, struct cgroup *cgroup)
    @@ -2090,6 +2299,7 @@ struct cgroup_subsys io_subsys = {
    .destroy = iocg_destroy,
    .populate = iocg_populate,
    .subsys_id = io_subsys_id,
    + .use_id = 1,
    };

    /*
    @@ -2380,6 +2590,22 @@ EXPORT_SYMBOL(elv_get_slice_idle);
    void elv_ioq_served(struct io_queue *ioq, bfq_service_t served)
    {
    entity_served(&ioq->entity, served, ioq->nr_sectors);
    +
    +#ifdef CONFIG_DEBUG_GROUP_IOSCHED
    + {
    + struct elv_fq_data *efqd = ioq->efqd;
    + struct io_group *iog = ioq_to_io_group(ioq);
    + elv_log_ioq(efqd, ioq, "ioq served: QSt=0x%lx QSs=0x%lx"
    + " QTt=0x%lx QTs=0x%lx GTt=0x%lx "
    + " GTs=0x%lx rq_queued=%d",
    + served, ioq->nr_sectors,
    + ioq->entity.total_service,
    + ioq->entity.total_sector_service,
    + iog->entity.total_service,
    + iog->entity.total_sector_service,
    + ioq->nr_queued);
    + }
    +#endif
    }

    /* Tells whether ioq is queued in root group or not */
    @@ -2847,10 +3073,30 @@ static void __elv_set_active_ioq(struct elv_fq_data *efqd, struct io_queue *ioq,
    if (ioq) {
    struct io_group *iog = ioq_to_io_group(ioq);
    elv_log_ioq(efqd, ioq, "set_active, busy=%d ioprio=%d"
    - " weight=%ld group_weight=%ld",
    + " weight=%ld rq_queued=%d group_weight=%ld",
    efqd->busy_queues,
    ioq->entity.ioprio, ioq->entity.weight,
    - iog_weight(iog));
    + ioq->nr_queued, iog_weight(iog));
    +
    +#ifdef CONFIG_DEBUG_GROUP_IOSCHED
    + {
    + int nr_active = 0;
    + struct io_group *parent = NULL;
    +
    + parent = iog_parent(iog);
    + if (parent)
    + nr_active = elv_iog_nr_active(parent);
    +
    + elv_log_ioq(efqd, ioq, "set_active, ioq"
    + " nrgrps=%d QTt=0x%lx QTs=0x%lx GTt=0x%lx "
    + " GTs=0x%lx rq_queued=%d", nr_active,
    + ioq->entity.total_service,
    + ioq->entity.total_sector_service,
    + iog->entity.total_service,
    + iog->entity.total_sector_service,
    + ioq->nr_queued);
    + }
    +#endif
    ioq->slice_end = 0;

    elv_clear_ioq_wait_request(ioq);
    @@ -2927,12 +3173,26 @@ void elv_add_ioq_busy(struct elv_fq_data *efqd, struct io_queue *ioq)
    {
    BUG_ON(elv_ioq_busy(ioq));
    BUG_ON(ioq == efqd->active_queue);
    - elv_log_ioq(efqd, ioq, "add to busy");
    elv_activate_ioq(ioq, 0);
    elv_mark_ioq_busy(ioq);
    efqd->busy_queues++;
    if (elv_ioq_class_rt(ioq))
    efqd->busy_rt_queues++;
    +
    +#ifdef CONFIG_DEBUG_GROUP_IOSCHED
    + {
    + struct io_group *iog = ioq_to_io_group(ioq);
    + elv_log_ioq(efqd, ioq, "add to busy: QTt=0x%lx QTs=0x%lx"
    + " ioq grp=%s GTt=0x%lx GTs=0x%lx rq_queued=%d",
    + ioq->entity.total_service,
    + ioq->entity.total_sector_service,
    + iog->entity.total_service,
    + iog->entity.total_sector_service,
    + ioq->nr_queued);
    + }
    +#else
    + elv_log_ioq(efqd, ioq, "add to busy");
    +#endif
    }

    void elv_del_ioq_busy(struct elevator_queue *e, struct io_queue *ioq,
    @@ -2942,7 +3202,21 @@ void elv_del_ioq_busy(struct elevator_queue *e, struct io_queue *ioq,

    BUG_ON(!elv_ioq_busy(ioq));
    BUG_ON(ioq->nr_queued);
    +#ifdef CONFIG_DEBUG_GROUP_IOSCHED
    + {
    + struct io_group *iog = ioq_to_io_group(ioq);
    + elv_log_ioq(efqd, ioq, "del from busy: QTt=0x%lx "
    + "QTs=0x%lx ioq GTt=0x%lx GTs=0x%lx "
    + "rq_queued=%d",
    + ioq->entity.total_service,
    + ioq->entity.total_sector_service,
    + iog->entity.total_service,
    + iog->entity.total_sector_service,
    + ioq->nr_queued);
    + }
    +#else
    elv_log_ioq(efqd, ioq, "del from busy");
    +#endif
    elv_clear_ioq_busy(ioq);
    BUG_ON(efqd->busy_queues == 0);
    efqd->busy_queues--;
    @@ -3179,6 +3453,7 @@ void elv_ioq_request_add(struct request_queue *q, struct request *rq)

    elv_ioq_update_io_thinktime(ioq);
    elv_ioq_update_idle_window(q->elevator, ioq, rq);
    + elv_log_ioq(efqd, ioq, "add rq: rq_queued=%d", ioq->nr_queued);

    if (ioq == elv_active_ioq(q->elevator)) {
    /*
    @@ -3412,7 +3687,7 @@ void *elv_fq_select_ioq(struct request_queue *q, int force)
    }

    /* We are waiting for this queue to become busy before it expires.*/
    - if (efqd->fairness && elv_ioq_wait_busy(ioq)) {
    + if (elv_ioq_wait_busy(ioq)) {
    ioq = NULL;
    goto keep_queue;
    }
    diff --git a/block/elevator-fq.h b/block/elevator-fq.h
    index ff409ec..b5cff90 100644
    --- a/block/elevator-fq.h
    +++ b/block/elevator-fq.h
    @@ -251,6 +251,23 @@ struct io_group {

    /* request list associated with the group */
    struct request_list rl;
    +
    +#ifdef CONFIG_DEBUG_GROUP_IOSCHED
    + /* How many times this group has been added to active tree */
    + unsigned long queue;
    +
    + /* How long this group remained on active tree, in ms */
    + unsigned long queue_duration;
    +
    + /* When was this group added to active tree */
    + unsigned long queue_start;
    +
    + /* How many times this group has been removed from active tree */
    + unsigned long dequeue;
    +
    + /* Store cgroup path */
    + char path[128];
    +#endif
    };

    struct io_policy_node {
    @@ -353,9 +370,18 @@ extern int elv_slice_idle;
    extern int elv_slice_async;

    /* Logging facilities. */
    +#ifdef CONFIG_DEBUG_GROUP_IOSCHED
    +#define elv_log_ioq(efqd, ioq, fmt, args...) \
    +{ \
    + blk_add_trace_msg((efqd)->queue, "elv%d%c %s " fmt, (ioq)->pid, \
    + elv_ioq_sync(ioq) ? 'S' : 'A', \
    + ioq_to_io_group(ioq)->path, ##args); \
    +}
    +#else
    #define elv_log_ioq(efqd, ioq, fmt, args...) \
    blk_add_trace_msg((efqd)->queue, "elv%d%c " fmt, (ioq)->pid, \
    elv_ioq_sync(ioq) ? 'S' : 'A', ##args)
    +#endif

    #define elv_log(efqd, fmt, args...) \
    blk_add_trace_msg((efqd)->queue, "elv " fmt, ##args)
    --
    1.6.0.6


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      Last update: 2009-06-09 04:19    [W:0.057 / U:152.528 seconds]
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