ANDROID: binder: show high watermark of alloc->pages.

Show the high watermark of the index into the alloc->pages
array, to facilitate sizing the buffer on a per-process
basis.

Change-Id: I2b40cd16628e0ee45216c51dc9b3c5b0c862032e
Signed-off-by: Martijn Coenen <maco@android.com>

drivers/android/binder_alloc.c

@@ -282,6 +282,9 @@ static int binder_update_page_range(struct binder_alloc *alloc, int allocate,
 			goto err_vm_insert_page_failed;
 		}
 
+		if (index + 1 > alloc->pages_high)
+			alloc->pages_high = index + 1;
+
 		trace_binder_alloc_page_end(alloc, index);
 		/* vm_insert_page does not seem to increment the refcount */
 	}
@@ -855,6 +858,7 @@ void binder_alloc_print_pages(struct seq_file *m,
 	}
 	mutex_unlock(&alloc->mutex);
 	seq_printf(m, "  pages: %d:%d:%d\n", active, lru, free);
+	seq_printf(m, "  pages high watermark: %zu\n", alloc->pages_high);
 }
 
 /**

drivers/android/binder_alloc.h

@@ -92,6 +92,7 @@ struct binder_lru_page {
  * @pages:              array of binder_lru_page
  * @buffer_size:        size of address space specified via mmap
  * @pid:                pid for associated binder_proc (invariant after init)
+ * @pages_high:         high watermark of offset in @pages
  *
  * Bookkeeping structure for per-proc address space management for binder
  * buffers. It is normally initialized during binder_init() and binder_mmap()
@@ -112,6 +113,7 @@ struct binder_alloc {
 	size_t buffer_size;
 	uint32_t buffer_free;
 	int pid;
+	size_t pages_high;
 };
 
 #ifdef CONFIG_ANDROID_BINDER_IPC_SELFTEST