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Subject[PATCH 24/24] io-controller: debug elevator fair queuing support
Date
o More debugging help to debug elevator fair queuing support. Enabled under
CONFIG_DEBUG_ELV_FAIR_QUEUING. Currently it prints vdisktime related
trace messages in blktrace.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
---
block/Kconfig.iosched | 9 +++++++++
block/elevator-fq.c | 47 ++++++++++++++++++++++++++++++++++++++++++++++-
2 files changed, 55 insertions(+), 1 deletions(-)

diff --git a/block/Kconfig.iosched b/block/Kconfig.iosched
index 8b507c4..edcd317 100644
--- a/block/Kconfig.iosched
+++ b/block/Kconfig.iosched
@@ -15,6 +15,15 @@ config ELV_FAIR_QUEUING
other ioschedulers can make use of it.
If unsure, say N.

+config DEBUG_ELV_FAIR_QUEUING
+ bool "Debug elevator fair queuing"
+ depends on ELV_FAIR_QUEUING
+ default n
+ ---help---
+ Enable some debugging hooks for elevator fair queuing support.
+ Currently it just outputs more information about vdisktime in
+ blktrace output .
+
config IOSCHED_NOOP
bool
default y
diff --git a/block/elevator-fq.c b/block/elevator-fq.c
index 2f7a419..d04e925 100644
--- a/block/elevator-fq.c
+++ b/block/elevator-fq.c
@@ -34,6 +34,24 @@ static struct kmem_cache *elv_ioq_pool;
#define ELV_SERVICE_TREE_INIT ((struct io_service_tree) \
{ RB_ROOT, NULL, 0, NULL, 0})

+#ifdef CONFIG_DEBUG_ELV_FAIR_QUEUING
+#define elv_log_entity(entity, fmt, args...) \
+{ \
+{ \
+ struct io_queue *ioq = ioq_of(entity); \
+ struct io_group *iog = iog_of(entity); \
+ \
+ if (ioq) { \
+ elv_log_ioq(ioq->efqd, ioq, fmt, ##args); \
+ } else { \
+ elv_log_iog((struct elv_fq_data *)iog->key, iog, fmt, ##args);\
+ } \
+} \
+}
+#else
+#define elv_log_entity(entity, fmt, args...)
+#endif
+
static inline struct io_queue *ioq_of(struct io_entity *entity)
{
if (entity->my_sd == NULL)
@@ -350,15 +368,39 @@ static inline void debug_update_stats_enqueue(struct io_entity *entity) {}
static inline void debug_update_stats_dequeue(struct io_entity *entity) {}
#endif /* DEBUG_GROUP_IOSCHED */

+#ifdef CONFIG_DEBUG_ELV_FAIR_QUEUING
+static inline void debug_entity_vdisktime(struct io_entity *entity,
+ unsigned long served, u64 delta)
+{
+ struct elv_fq_data *efqd;
+ struct io_group *iog;
+
+ elv_log_entity(entity, "vdisktime=%llu service=%lu delta=%llu"
+ " entity->weight=%u", entity->vdisktime,
+ served, delta, entity->weight);
+
+ iog = iog_of(parent_entity(entity));
+ efqd = iog->key;
+ elv_log_iog(efqd, iog, "min_vdisktime=%llu", entity->st->min_vdisktime);
+}
+#else /* DEBUG_ELV_FAIR_QUEUING */
+static inline void debug_entity_vdisktime(struct io_entity *entity,
+ unsigned long served, u64 delta) {}
+#endif /* DEBUG_ELV_FAIR_QUEUING */
+
static void
entity_served(struct io_entity *entity, unsigned long served,
unsigned long nr_sectors)
{
for_each_entity(entity) {
- entity->vdisktime += elv_delta_fair(served, entity);
+ u64 delta;
+
+ delta = elv_delta_fair(served, entity);
+ entity->vdisktime += delta;
update_min_vdisktime(entity->st);
entity->total_time += served;
entity->total_sectors += nr_sectors;
+ debug_entity_vdisktime(entity, served, delta);
}
}

@@ -391,6 +433,9 @@ static void place_entity(struct io_service_tree *st, struct io_entity *entity,
vdisktime = st->min_vdisktime;

entity->vdisktime = max_vdisktime(st->min_vdisktime, vdisktime);
+ elv_log_entity(entity, "place_entity: vdisktime=%llu"
+ " min_vdisktime=%llu", entity->vdisktime,
+ st->min_vdisktime);
}

static inline void io_entity_update_prio(struct io_entity *entity)
--
1.6.0.6


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