[PATCH 10/12] writeback: trace dirty_ratelimit

[Wu Fengguang]

It provides critical information to understand how various throttle
bandwidths are updated.

Signed-off-by: Wu Fengguang <fengguang.wu@xxxxxxxxx>
---
 include/trace/events/writeback.h |   51 +++++++++++++++++++++++++++--
 mm/page-writeback.c              |    1 
 2 files changed, 49 insertions(+), 3 deletions(-)

--- linux-next.orig/mm/page-writeback.c	2011-04-16 11:28:21.000000000 +0800
+++ linux-next/mm/page-writeback.c	2011-04-16 11:28:27.000000000 +0800
@@ -974,6 +974,7 @@ adjust:
 	bdi->dirty_ratelimit = bw;
 out:
 	bdi_update_reference_ratelimit(bdi, ref_bw);
+	trace_dirty_ratelimit(bdi, dirty_bw, pos_bw, ref_bw);
 }
 
 void bdi_update_bandwidth(struct backing_dev_info *bdi,
--- linux-next.orig/include/trace/events/writeback.h	2011-04-16 11:28:17.000000000 +0800
+++ linux-next/include/trace/events/writeback.h	2011-04-16 11:28:27.000000000 +0800
@@ -147,11 +147,56 @@ DEFINE_EVENT(wbc_class, name, \
 DEFINE_WBC_EVENT(wbc_writeback_start);
 DEFINE_WBC_EVENT(wbc_writeback_written);
 DEFINE_WBC_EVENT(wbc_writeback_wait);
-DEFINE_WBC_EVENT(wbc_balance_dirty_start);
-DEFINE_WBC_EVENT(wbc_balance_dirty_written);
-DEFINE_WBC_EVENT(wbc_balance_dirty_wait);
 DEFINE_WBC_EVENT(wbc_writepage);
 
+#define KBps(x)			((x) << (PAGE_SHIFT - 10))
+
+TRACE_EVENT(dirty_ratelimit,
+
+	TP_PROTO(struct backing_dev_info *bdi,
+		 unsigned long dirty_bw,
+		 unsigned long pos_bw,
+		 unsigned long ref_bw),
+
+	TP_ARGS(bdi, dirty_bw, pos_bw, ref_bw),
+
+	TP_STRUCT__entry(
+		__array(char,		bdi, 32)
+		__field(unsigned long,	write_bw)
+		__field(unsigned long,	avg_bw)
+		__field(unsigned long,	dirty_bw)
+		__field(unsigned long,	base_bw)
+		__field(unsigned long,	pos_bw)
+		__field(unsigned long,	ref_bw)
+		__field(unsigned long,	avg_ref_bw)
+	),
+
+	TP_fast_assign(
+		strlcpy(__entry->bdi, dev_name(bdi->dev), 32);
+		__entry->write_bw	= KBps(bdi->write_bandwidth);
+		__entry->avg_bw		= KBps(bdi->avg_write_bandwidth);
+		__entry->dirty_bw	= KBps(dirty_bw);
+		__entry->base_bw	= KBps(bdi->dirty_ratelimit);
+		__entry->pos_bw		= KBps(pos_bw);
+		__entry->ref_bw		= KBps(ref_bw);
+		__entry->avg_ref_bw	= KBps(bdi->reference_ratelimit);
+	),
+
+
+	TP_printk("bdi %s: "
+		  "write_bw=%lu awrite_bw=%lu dirty_bw=%lu "
+		  "base_bw=%lu pos_bw=%lu ref_bw=%lu aref_bw=%lu",
+		  __entry->bdi,
+		  __entry->write_bw,	/* write bandwidth */
+		  __entry->avg_bw,	/* avg write bandwidth */
+		  __entry->dirty_bw,	/* dirty bandwidth */
+		  __entry->base_bw,	/* dirty ratelimit on each task */
+		  __entry->pos_bw,	/* position control ratelimit */
+		  __entry->ref_bw,	/* the reference ratelimit */
+		  __entry->avg_ref_bw	/* smoothed reference ratelimit */
+	)
+);
+
 DECLARE_EVENT_CLASS(writeback_congest_waited_template,
 
 	TP_PROTO(unsigned int usec_timeout, unsigned int usec_delayed),


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