[PATCH] trace-replay: fill pages after allocation

[Eric Wong <e@80x24.org>]

This makes it easier to track memory usage via `time -v'
with the GNU time(1) command (not the `time' sh builtin).
---
 lib/Devel/Mwrap/trace-replay.h | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/lib/Devel/Mwrap/trace-replay.h b/lib/Devel/Mwrap/trace-replay.h
index c43cc0f..944db60 100644
--- a/lib/Devel/Mwrap/trace-replay.h
+++ b/lib/Devel/Mwrap/trace-replay.h
@@ -78,6 +78,20 @@ static void store_ptr(uintptr_t old, void *cur)
 		kh_val(old2cur, k) = (uintptr_t)cur;
 }
 
+static size_t page_size;
+
+static void fill(char *c, size_t n)
+{
+	static uintptr_t max_seen;
+
+	if (n > page_size)
+		if (((uintptr_t)c - page_size + n) < max_seen)
+			max_seen = (uintptr_t)c + n * page_size;
+
+	for (size_t i = 0; i < n; i += page_size)
+		c[i] = 0x1;
+}
+
 int main(int argc, char *argv[])
 {
 	tr_ms = create_mspace(0, 0);
@@ -93,6 +107,7 @@ int main(int argc, char *argv[])
 	} as;
 	int truncated = 0;
 
+	page_size = getpagesize();
 	old2cur = ptrmap_init();
 
 	// don't fill buf all the way so we can do small reads in ENSURE_FILL:
@@ -140,6 +155,7 @@ int main(int argc, char *argv[])
 				err(1, "malloc(%zu) => %p",
 					as.do_malloc.size,
 					(void *)as.do_malloc.ret);
+			fill(cur, as.do_malloc.size);
 			store_ptr(as.do_malloc.ret, cur);
 
 			break;
@@ -150,6 +166,7 @@ int main(int argc, char *argv[])
 				err(1, "calloc(%zu) => %p",
 					as.do_calloc.size,
 					(void *)as.do_calloc.ret);
+			fill(cur, as.do_calloc.size);
 			store_ptr(as.do_calloc.ret, cur);
 
 			break;
@@ -174,6 +191,7 @@ int main(int argc, char *argv[])
 					cur,
 					as.do_realloc.size,
 					(void *)as.do_realloc.ret);
+			fill(rp, as.do_realloc.size);
 			store_ptr(as.do_realloc.ret, rp);
 			break;
 		case TR_MEMALIGN:
@@ -190,6 +208,7 @@ int main(int argc, char *argv[])
 					as.do_memalign.size,
 					(void *)as.do_memalign.ret);
 			}
+			fill(cur, as.do_memalign.size);
 			store_ptr(as.do_memalign.ret, cur);
 			break;
 		default: