bdi write bandwidth estimation

@@ -40,6 +40,7 @@ typedef int (congested_fn)(void *, int);
 enum bdi_stat_item {
 	BDI_RECLAIMABLE,
 	BDI_WRITEBACK,
+	BDI_WRITTEN,
 	NR_BDI_STAT_ITEMS
 };
 

@@ -97,6 +97,7 @@ static int bdi_debug_stats_show(struct s
 		   "BdiDirtyThresh:   %8lu kB\n"
 		   "DirtyThresh:      %8lu kB\n"
 		   "BackgroundThresh: %8lu kB\n"
+		   "BdiWritten:       %8lu kB\n"
 		   "b_dirty:          %8lu\n"
 		   "b_io:             %8lu\n"
 		   "b_more_io:        %8lu\n"

@@ -104,8 +105,13 @@ static int bdi_debug_stats_show(struct s
 		   "state:            %8lx\n",
 		   (unsigned long) K(bdi_stat(bdi, BDI_WRITEBACK)),
 		   (unsigned long) K(bdi_stat(bdi, BDI_RECLAIMABLE)),
-		   K(bdi_thresh), K(dirty_thresh),
-		   K(background_thresh), nr_dirty, nr_io, nr_more_io,
+		   K(bdi_thresh),
+		   K(dirty_thresh),
+		   K(background_thresh),
+		   (unsigned long) K(bdi_stat(bdi, BDI_WRITTEN)),
+		   nr_dirty,
+		   nr_io,
+		   nr_more_io,
 		   !list_empty(&bdi->bdi_list), bdi->state);
 #undef K
 

@@ -219,6 +219,7 @@ int dirty_bytes_handler(struct ctl_table
  */
 static inline void __bdi_writeout_inc(struct backing_dev_info *bdi)
 {
+	__inc_bdi_stat(bdi, BDI_WRITTEN);
 	__prop_inc_percpu_max(&vm_completions, &bdi->completions,
 			      bdi->max_prop_frac);
 }

@@ -629,6 +629,16 @@ static inline bool over_bground_thresh(v
 }
 
 /*
+ * Called under &wb->list_lock. If there are multiple wb per bdi,
+ * only the flusher working on the first wb should do it.
+ */
+static void wb_update_bandwidth(struct bdi_writeback *wb,
+				unsigned long start_time)
+{
+	__bdi_update_bandwidth(wb->bdi, start_time);
+}
+
+/*
  * Explicit flushing or periodic writeback of "old" data.
  *
  * Define "old": the first time one of an inode's pages is dirtied, we mark the

@@ -658,6 +668,7 @@ static long wb_writeback(struct bdi_writ
 	long wrote = 0;
 	long write_chunk = MAX_WRITEBACK_PAGES;
 	struct inode *inode;
+	unsigned long wb_start = jiffies;
 
 	if (!wbc.range_cyclic) {
 		wbc.range_start = 0;

@@ -727,6 +738,8 @@ static long wb_writeback(struct bdi_writ
 			__writeback_inodes_wb(wb, &wbc);
 		trace_wbc_writeback_written(&wbc, wb->bdi);
 
+		wb_update_bandwidth(wb, wb_start);
+
 		work->nr_pages -= write_chunk - wbc.nr_to_write;
 		wrote += write_chunk - wbc.nr_to_write;
 

@@ -73,6 +73,11 @@ struct backing_dev_info {
 
 	struct percpu_counter bdi_stat[NR_BDI_STAT_ITEMS];
 
+	unsigned long bw_time_stamp;
+	unsigned long written_stamp;
+	unsigned long write_bandwidth;
+	unsigned long avg_write_bandwidth;
+
 	struct prop_local_percpu completions;
 	int dirty_exceeded;
 

@@ -122,6 +122,9 @@ void global_dirty_limits(unsigned long *
 unsigned long bdi_dirty_limit(struct backing_dev_info *bdi,
 			       unsigned long dirty);
 
+void __bdi_update_bandwidth(struct backing_dev_info *bdi,
+			    unsigned long start_time);
+
 void page_writeback_init(void);
 void balance_dirty_pages_ratelimited_nr(struct address_space *mapping,
 					unsigned long nr_pages_dirtied);

@@ -649,6 +649,11 @@ static void bdi_wb_init(struct bdi_write
 	setup_timer(&wb->wakeup_timer, wakeup_timer_fn, (unsigned long)bdi);
 }
 
+/*
+ * Initial write bandwidth: 100 MB/s
+ */
+#define INIT_BW		(100 << (20 - PAGE_SHIFT))
+
 int bdi_init(struct backing_dev_info *bdi)
 {
 	int i, err;

@@ -671,6 +676,13 @@ int bdi_init(struct backing_dev_info *bd
 	}
 
 	bdi->dirty_exceeded = 0;
+
+	bdi->bw_time_stamp = jiffies;
+	bdi->written_stamp = 0;
+
+	bdi->write_bandwidth = INIT_BW;
+	bdi->avg_write_bandwidth = INIT_BW;
+
 	err = prop_local_init_percpu(&bdi->completions);
 
 	if (err) {

105 lines not on this page · raw message

@@ -92,23 +92,25 @@ static int bdi_debug_stats_show(struct s
 
 #define K(x) ((x) << (PAGE_SHIFT - 10))
 	seq_printf(m,
-		   "BdiWriteback:     %8lu kB\n"
-		   "BdiReclaimable:   %8lu kB\n"
-		   "BdiDirtyThresh:   %8lu kB\n"
-		   "DirtyThresh:      %8lu kB\n"
-		   "BackgroundThresh: %8lu kB\n"
-		   "BdiWritten:       %8lu kB\n"
-		   "b_dirty:          %8lu\n"
-		   "b_io:             %8lu\n"
-		   "b_more_io:        %8lu\n"
-		   "bdi_list:         %8u\n"
-		   "state:            %8lx\n",
+		   "BdiWriteback:       %10lu kB\n"
+		   "BdiReclaimable:     %10lu kB\n"
+		   "BdiDirtyThresh:     %10lu kB\n"
+		   "DirtyThresh:        %10lu kB\n"
+		   "BackgroundThresh:   %10lu kB\n"
+		   "BdiWritten:         %10lu kB\n"
+		   "BdiWriteBandwidth:  %10lu kBps\n"
+		   "b_dirty:            %10lu\n"
+		   "b_io:               %10lu\n"
+		   "b_more_io:          %10lu\n"
+		   "bdi_list:           %10u\n"
+		   "state:              %10lx\n",
 		   (unsigned long) K(bdi_stat(bdi, BDI_WRITEBACK)),
 		   (unsigned long) K(bdi_stat(bdi, BDI_RECLAIMABLE)),
 		   K(bdi_thresh),
 		   K(dirty_thresh),
 		   K(background_thresh),
 		   (unsigned long) K(bdi_stat(bdi, BDI_WRITTEN)),
+		   (unsigned long) K(bdi->write_bandwidth),
 		   nr_dirty,
 		   nr_io,
 		   nr_more_io,