[PATCH v2] block: Add ioprio to block_rq tracepoint

[Dongliang Cui]

Sometimes we need to track the processing order of requests with
ioprio set. So the ioprio of request can be useful information.

Example：

block_rq_insert: 8,0 WS 4096 () 16573296 + 8 rt,4 [highpool[1]]
block_rq_issue: 8,0 WS 4096 () 16573296 + 8 rt,4 [kworker/7:0H]
block_rq_complete: 8,0 WS () 16573296 + 8 rt,4 [0]

Signed-off-by: Dongliang Cui <dongliang.cui@xxxxxxxxxx>

Changes history
Changes in v2:
Update the printing method of ioprio_class.
---
 include/trace/events/block.h | 36 ++++++++++++++++++++++++++----------
 include/uapi/linux/ioprio.h  |  7 +++++++
 2 files changed, 33 insertions(+), 10 deletions(-)

diff --git a/include/trace/events/block.h b/include/trace/events/block.h
index 0e128ad51460..8aa0116077ee 100644
--- a/include/trace/events/block.h
+++ b/include/trace/events/block.h
@@ -9,6 +9,7 @@
 #include <linux/blkdev.h>
 #include <linux/buffer_head.h>
 #include <linux/tracepoint.h>
+#include <uapi/linux/ioprio.h>
 
 #define RWBS_LEN	8
 
@@ -82,6 +83,8 @@ TRACE_EVENT(block_rq_requeue,
 		__field(  dev_t,	dev			)
 		__field(  sector_t,	sector			)
 		__field(  unsigned int,	nr_sector		)
+		__field(  unsigned int,	ioprio_class		)
+		__field(  unsigned int, ioprio_value		)
 		__array(  char,		rwbs,	RWBS_LEN	)
 		__dynamic_array( char,	cmd,	1		)
 	),
@@ -90,16 +93,19 @@ TRACE_EVENT(block_rq_requeue,
 		__entry->dev	   = rq->q->disk ? disk_devt(rq->q->disk) : 0;
 		__entry->sector    = blk_rq_trace_sector(rq);
 		__entry->nr_sector = blk_rq_trace_nr_sectors(rq);
+		__entry->ioprio_class = rq->ioprio >> IOPRIO_CLASS_SHIFT & 0x3;
+		__entry->ioprio_value = rq->ioprio & 0xff;
 
 		blk_fill_rwbs(__entry->rwbs, rq->cmd_flags);
 		__get_str(cmd)[0] = '\0';
 	),
 
-	TP_printk("%d,%d %s (%s) %llu + %u [%d]",
+	TP_printk("%d,%d %s (%s) %llu + %u %s,%u [%d]",
 		  MAJOR(__entry->dev), MINOR(__entry->dev),
 		  __entry->rwbs, __get_str(cmd),
-		  (unsigned long long)__entry->sector,
-		  __entry->nr_sector, 0)
+		  (unsigned long long)__entry->sector, __entry->nr_sector,
+		  __print_symbolic(__entry->ioprio_class, IOPRIO_CLASS_STRINGS),
+		  __entry->ioprio_value, 0)
 );
 
 DECLARE_EVENT_CLASS(block_rq_completion,
@@ -113,6 +119,8 @@ DECLARE_EVENT_CLASS(block_rq_completion,
 		__field(  sector_t,	sector			)
 		__field(  unsigned int,	nr_sector		)
 		__field(  int	,	error			)
+		__field(  unsigned int,	ioprio_class		)
+		__field(  unsigned int, ioprio_value		)
 		__array(  char,		rwbs,	RWBS_LEN	)
 		__dynamic_array( char,	cmd,	1		)
 	),
@@ -122,16 +130,19 @@ DECLARE_EVENT_CLASS(block_rq_completion,
 		__entry->sector    = blk_rq_pos(rq);
 		__entry->nr_sector = nr_bytes >> 9;
 		__entry->error     = blk_status_to_errno(error);
+		__entry->ioprio_class = rq->ioprio >> IOPRIO_CLASS_SHIFT & 0x3;
+		__entry->ioprio_value = rq->ioprio & 0xff;
 
 		blk_fill_rwbs(__entry->rwbs, rq->cmd_flags);
 		__get_str(cmd)[0] = '\0';
 	),
 
-	TP_printk("%d,%d %s (%s) %llu + %u [%d]",
+	TP_printk("%d,%d %s (%s) %llu + %u %s,%u [%d]",
 		  MAJOR(__entry->dev), MINOR(__entry->dev),
 		  __entry->rwbs, __get_str(cmd),
-		  (unsigned long long)__entry->sector,
-		  __entry->nr_sector, __entry->error)
+		  (unsigned long long)__entry->sector, __entry->nr_sector,
+		  __print_symbolic(__entry->ioprio_class, IOPRIO_CLASS_STRINGS),
+		  __entry->ioprio_value, __entry->error)
 );
 
 /**
@@ -180,8 +191,10 @@ DECLARE_EVENT_CLASS(block_rq,
 		__field(  sector_t,	sector			)
 		__field(  unsigned int,	nr_sector		)
 		__field(  unsigned int,	bytes			)
+		__field(  unsigned int,	ioprio_class		)
+		__field(  unsigned int, ioprio_value		)
 		__array(  char,		rwbs,	RWBS_LEN	)
-		__array(  char,         comm,   TASK_COMM_LEN   )
+		__array(  char,		comm,   TASK_COMM_LEN	)
 		__dynamic_array( char,	cmd,	1		)
 	),
 
@@ -190,17 +203,20 @@ DECLARE_EVENT_CLASS(block_rq,
 		__entry->sector    = blk_rq_trace_sector(rq);
 		__entry->nr_sector = blk_rq_trace_nr_sectors(rq);
 		__entry->bytes     = blk_rq_bytes(rq);
+		__entry->ioprio_class = rq->ioprio >> IOPRIO_CLASS_SHIFT & 0x3;
+		__entry->ioprio_value = rq->ioprio & 0xff;
 
 		blk_fill_rwbs(__entry->rwbs, rq->cmd_flags);
 		__get_str(cmd)[0] = '\0';
 		memcpy(__entry->comm, current->comm, TASK_COMM_LEN);
 	),
 
-	TP_printk("%d,%d %s %u (%s) %llu + %u [%s]",
+	TP_printk("%d,%d %s %u (%s) %llu + %u %s,%u [%s]",
 		  MAJOR(__entry->dev), MINOR(__entry->dev),
 		  __entry->rwbs, __entry->bytes, __get_str(cmd),
-		  (unsigned long long)__entry->sector,
-		  __entry->nr_sector, __entry->comm)
+		  (unsigned long long)__entry->sector, __entry->nr_sector,
+		  __print_symbolic(__entry->ioprio_class, IOPRIO_CLASS_STRINGS),
+		  __entry->ioprio_value, __entry->comm)
 );
 
 /**
diff --git a/include/uapi/linux/ioprio.h b/include/uapi/linux/ioprio.h
index bee2bdb0eedb..9a43ad3a65ab 100644
--- a/include/uapi/linux/ioprio.h
+++ b/include/uapi/linux/ioprio.h
@@ -35,6 +35,13 @@ enum {
 	IOPRIO_CLASS_INVALID	= 7,
 };
 
+#define IOPRIO_CLASS_STRINGS \
+	{ IOPRIO_CLASS_NONE,	"none" }, \
+	{ IOPRIO_CLASS_RT,	"rt" }, \
+	{ IOPRIO_CLASS_BE,	"be" }, \
+	{ IOPRIO_CLASS_IDLE,	"idle" }, \
+	{ IOPRIO_CLASS_INVALID,	"invalid" }
+
 /*
  * The RT and BE priority classes both support up to 8 priority levels that
  * can be specified using the lower 3-bits of the priority data.
-- 
2.25.1