writeback: trace global_dirty_state

Add trace event balance_dirty_state for showing the global dirty page
counts and thresholds at each global_dirty_limits() invocation.  This
will cover the callers throttle_vm_writeout(), over_bground_thresh()
and each balance_dirty_pages() loop.

Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>

1 files changed, 46 insertions, 0 deletions

diff --git a/include/trace/events/writeback.h b/include/trace/events/writeback.h
index 3e7662a0cfa3..6bca4cc0063c 100644
--- a/include/trace/events/writeback.h
+++ b/include/trace/events/writeback.h
@@ -204,6 +204,52 @@ TRACE_EVENT(writeback_queue_io,
                 __entry->moved)
 );
 
+TRACE_EVENT(global_dirty_state,
+
+        TP_PROTO(unsigned long background_thresh,
+                 unsigned long dirty_thresh
+        ),
+
+        TP_ARGS(background_thresh,
+                dirty_thresh
+        ),
+
+        TP_STRUCT__entry(
+                __field(unsigned long,  nr_dirty)
+                __field(unsigned long,  nr_writeback)
+                __field(unsigned long,  nr_unstable)
+                __field(unsigned long,  background_thresh)
+                __field(unsigned long,  dirty_thresh)
+                __field(unsigned long,  dirty_limit)
+                __field(unsigned long,  nr_dirtied)
+                __field(unsigned long,  nr_written)
+        ),
+
+        TP_fast_assign(
+                __entry->nr_dirty       = global_page_state(NR_FILE_DIRTY);
+                __entry->nr_writeback   = global_page_state(NR_WRITEBACK);
+                __entry->nr_unstable    = global_page_state(NR_UNSTABLE_NFS);
+                __entry->nr_dirtied     = global_page_state(NR_DIRTIED);
+                __entry->nr_written     = global_page_state(NR_WRITTEN);
+                __entry->background_thresh = background_thresh;
+                __entry->dirty_thresh   = dirty_thresh;
+                __entry->dirty_limit = global_dirty_limit;
+        ),
+
+        TP_printk("dirty=%lu writeback=%lu unstable=%lu "
+                  "bg_thresh=%lu thresh=%lu limit=%lu "
+                  "dirtied=%lu written=%lu",
+                  __entry->nr_dirty,
+                  __entry->nr_writeback,
+                  __entry->nr_unstable,
+                  __entry->background_thresh,
+                  __entry->dirty_thresh,
+                  __entry->dirty_limit,
+                  __entry->nr_dirtied,
+                  __entry->nr_written
+        )
+);
+
 DECLARE_EVENT_CLASS(writeback_congest_waited_template,
 
         TP_PROTO(unsigned int usec_timeout, unsigned int usec_delayed),