lib/os/heap: make printed heap info more useful

Turn sys_heap_dump() into sys_heap_print_info() to better reflect
what it actually does, and improve the information being printed.

Signed-off-by: Nicolas Pitre <npitre@baylibre.com>

include/sys/sys_heap.h

@@ -201,13 +201,14 @@ void sys_heap_stress(void *(*alloc)(void *arg, size_t bytes),
 		     int target_percent,
 		     struct z_heap_stress_result *result);
 
-/** @brief Dump heap structure content for debugging to the console
+/** @brief Print heap internal structure information to the console
  *
- * Print information on the heap structure such as its size, chunk buckets
- * and chunk list.
+ * Print information on the heap structure such as its size, chunk buckets,
+ * chunk list and some statistics for debugging purpose.
  *
  * @param h Heap to print information about
+ * @param dump_chunks True to print the entire heap chunk list
  */
-void sys_heap_dump(struct sys_heap *h);
+void sys_heap_print_info(struct sys_heap *h, bool dump_chunks);
 
 #endif /* ZEPHYR_INCLUDE_SYS_SYS_HEAP_H_ */

lib/os/heap-validate.c

@@ -314,41 +314,81 @@ void sys_heap_stress(void *(*alloc)(void *arg, size_t bytes),
 }
 
 /*
- * Dump heap structure content for debugging / analysis purpose
+ * Print heap info for debugging / analysis purpose
  */
-void heap_dump(struct z_heap *h)
+void heap_print_info(struct z_heap *h, bool dump_chunks)
 {
 	int i, nb_buckets = bucket_idx(h, h->len) + 1;
+	size_t free_bytes, allocated_bytes, total, overhead;
 
-	printk("Heap at %p contains %d units\n", chunk_buf(h), h->len);
+	printk("Heap at %p contains %d units in %d buckets\n\n",
+	       chunk_buf(h), h->len, nb_buckets);
 
+	printk("  bucket#    min units        total      largest      largest\n"
+	       "             threshold       chunks      (units)      (bytes)\n"
+	       "  -----------------------------------------------------------\n");
 	for (i = 0; i < nb_buckets; i++) {
 		chunkid_t first = h->buckets[i].next;
+		size_t largest = 0;
 		int count = 0;
 
 		if (first) {
 			chunkid_t curr = first;
 			do {
 				count++;
+				largest = MAX(largest, chunk_size(h, curr));
 				curr = next_free_chunk(h, curr);
 			} while (curr != first);
 		}
-
-		printk("bucket %d (min %d units): %d chunks\n", i,
-		       (1 << i) - 1 + min_chunk_size(h), count);
+		if (count) {
+			printk("%9d %12d %12d %12zd %12zd\n",
+			       i, (1 << i) - 1 + min_chunk_size(h), count,
+			       largest, largest * CHUNK_UNIT - chunk_header_bytes(h));
+		}
 	}
 
+	if (dump_chunks) {
+		printk("\nChunk dump:\n");
+	}
+	free_bytes = allocated_bytes = 0;
 	for (chunkid_t c = 0; ; c = right_chunk(h, c)) {
-		printk("chunk %3zd: %c %3zd] %3zd [%zd\n",
-		       c, chunk_used(h, c) ? '*' : '-',
-		      left_chunk(h, c), chunk_size(h, c), right_chunk(h, c));
+		if (c == 0 || c == h->len) {
+			/* those are always allocated for internal purposes */
+		} else if (chunk_used(h, c)) {
+			allocated_bytes += chunk_size(h, c) * CHUNK_UNIT
+						- chunk_header_bytes(h);
+		} else if (!solo_free_header(h, c)) {
+			free_bytes += chunk_size(h, c) * CHUNK_UNIT
+						- chunk_header_bytes(h);
+		}
+		if (dump_chunks) {
+			printk("chunk %4zd: [%c] size=%-4zd left=%-4zd right=%zd\n",
+			       c,
+			       chunk_used(h, c) ? '*'
+			       : solo_free_header(h, c) ? '.'
+			       : '-',
+			       chunk_size(h, c),
+			       left_chunk(h, c),
+			       right_chunk(h, c));
+		}
 		if (c == h->len) {
 			break;
 		}
 	}
+
+	/*
+	 * The final chunk at h->len  is just a header serving as a end
+	 * marker. It is part of the overhead.
+	 */
+	total = h->len * CHUNK_UNIT + chunk_header_bytes(h);
+	overhead = total - free_bytes - allocated_bytes;
+	printk("\n%zd free bytes, %zd allocated bytes, overhead = %zd bytes (%zd.%zd%%)\n",
+	       free_bytes, allocated_bytes, overhead,
+	       (1000 * overhead + total/2) / total / 10,
+	       (1000 * overhead + total/2) / total % 10);
 }
 
-void sys_heap_dump(struct sys_heap *heap)
+void sys_heap_print_info(struct sys_heap *heap, bool dump_chunks)
 {
-	heap_dump(heap->heap);
+	heap_print_info(heap->heap, dump_chunks);
 }

lib/os/heap.h

@@ -240,6 +240,6 @@ static inline bool size_too_big(struct z_heap *h, size_t bytes)
 }
 
 /* For debugging */
-void heap_dump(struct z_heap *h);
+void heap_print_info(struct z_heap *h, bool dump_chunks);
 
 #endif /* ZEPHYR_INCLUDE_LIB_OS_HEAP_H_ */