[PATCH 18/19] io-controller: Debug hierarchical IO scheduling

From: Vivek Goyal
Date: Mon Jun 08 2009 - 22:12:34 EST

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@xxxxxxxxxx>
---
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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