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Subject[PATCH 11/16] blkio: Some debugging aids for CFQ
Date
o Some debugging aids for CFQ.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
---
block/Kconfig | 9 +++++++++
block/Kconfig.iosched | 9 +++++++++
block/blk-cgroup.c | 4 ++++
block/blk-cgroup.h | 13 +++++++++++++
block/cfq-iosched.c | 17 +++++++++++++++++
5 files changed, 52 insertions(+), 0 deletions(-)
diff --git a/block/Kconfig b/block/Kconfig
index 6ba1a8e..e20fbde 100644
--- a/block/Kconfig
+++ b/block/Kconfig
@@ -90,6 +90,15 @@ config BLK_CGROUP
control disk bandwidth allocation (proportional time slice allocation)
to such task groups.

+config DEBUG_BLK_CGROUP
+ bool
+ depends on BLK_CGROUP
+ default n
+ ---help---
+ Enable some debugging help. Currently it stores the cgroup path
+ in the blk group which can be used by cfq for tracing various
+ group related activity.
+
endif # BLOCK

config BLOCK_COMPAT
diff --git a/block/Kconfig.iosched b/block/Kconfig.iosched
index fa95fa7..b71abfb 100644
--- a/block/Kconfig.iosched
+++ b/block/Kconfig.iosched
@@ -40,6 +40,15 @@ config CFQ_GROUP_IOSCHED
---help---
Enable group IO scheduling in CFQ.

+config DEBUG_CFQ_IOSCHED
+ bool "Debug CFQ Scheduling"
+ depends on CFQ_GROUP_IOSCHED
+ select DEBUG_BLK_CGROUP
+ default n
+ ---help---
+ Enable CFQ IO scheduling debugging in CFQ. Currently it makes
+ blktrace output more verbose.
+
choice
prompt "Default I/O scheduler"
default DEFAULT_CFQ
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 0426ab6..6bc99a3 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -33,6 +33,10 @@ void blkiocg_add_blkio_group(struct blkio_cgroup *blkcg,
blkg->blkcg_id = css_id(&blkcg->css);
hlist_add_head_rcu(&blkg->blkcg_node, &blkcg->blkg_list);
spin_unlock_irqrestore(&blkcg->lock, flags);
+#ifdef CONFIG_DEBUG_BLK_CGROUP
+ /* Need to take css reference ? */
+ cgroup_path(blkcg->css.cgroup, blkg->path, sizeof(blkg->path));
+#endif
}

static void __blkiocg_del_blkio_group(struct blkio_group *blkg)
diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h
index cd50a2f..3573199 100644
--- a/block/blk-cgroup.h
+++ b/block/blk-cgroup.h
@@ -27,12 +27,25 @@ struct blkio_group {
void *key;
struct hlist_node blkcg_node;
unsigned short blkcg_id;
+#ifdef CONFIG_DEBUG_BLK_CGROUP
+ /* Store cgroup path */
+ char path[128];
+#endif
};

#define BLKIO_WEIGHT_MIN 100
#define BLKIO_WEIGHT_MAX 1000
#define BLKIO_WEIGHT_DEFAULT 500

+#ifdef CONFIG_DEBUG_BLK_CGROUP
+static inline char *blkg_path(struct blkio_group *blkg)
+{
+ return blkg->path;
+}
+#else
+static inline char *blkg_path(struct blkio_group *blkg) { return NULL; }
+#endif
+
#ifdef CONFIG_BLK_CGROUP
extern struct blkio_cgroup blkio_root_cgroup;
extern struct blkio_cgroup *cgroup_to_blkio_cgroup(struct cgroup *cgroup);
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index de21882..6b30a6b 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -331,8 +331,21 @@ CFQ_CFQQ_FNS(sync);
CFQ_CFQQ_FNS(coop);
#undef CFQ_CFQQ_FNS

+#ifdef CONFIG_DEBUG_CFQ_IOSCHED
+#define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
+ blk_add_trace_msg((cfqd)->queue, "cfq%d%c %s " fmt, (cfqq)->pid, \
+ cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \
+ blkg_path(&(cfqq)->cfqg->blkg), ##args);
+
+#define cfq_log_cfqg(cfqd, cfqg, fmt, args...) \
+ blk_add_trace_msg((cfqd)->queue, "%s " fmt, \
+ blkg_path(&(cfqg)->blkg), ##args); \
+
+#else
#define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args)
+#define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do{}while(0);
+#endif
#define cfq_log(cfqd, fmt, args...) \
blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)

@@ -796,6 +809,7 @@ cfq_group_service_tree_del(struct cfq_data *cfqd, struct cfq_group *cfqg)
if (cfqg->nr_cfqq)
return;

+ cfq_log_cfqg(cfqd, cfqg, "del_from_rr group");
cfqg->on_st = false;
cfqd->nr_groups--;
if (!RB_EMPTY_NODE(&cfqg->rb_node))
@@ -849,6 +863,9 @@ static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg,
cfqg->saved_serving_prio = cfqd->serving_prio;
} else
cfqg->saved_workload_slice = 0;
+
+ cfq_log_cfqg(cfqd, cfqg, "served: vt=%llu min_vt=%llu", cfqg->vdisktime,
+ st->min_vdisktime);
}

#ifdef CONFIG_CFQ_GROUP_IOSCHED
--
1.6.2.5


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