From: Matt Mullins <mmullins@mmlx.us>
Date: Sat, 21 Sep 2013 02:57:32 +0000 (-0700)
Subject: Map all the memory, shrinking block size as necessary
X-Git-Url: http://git.mmlx.us/?a=commitdiff_plain;h=ec5d5f360206747543d17188511f223fec24ae92;p=mmap_everything.git

Map all the memory, shrinking block size as necessary
---

diff --git a/mmap_everything.c b/mmap_everything.c
index 2d24390..2940a11 100644
--- a/mmap_everything.c
+++ b/mmap_everything.c
@@ -1,18 +1,23 @@
+#include <limits.h>
 #include <sys/mman.h>
 #include <sys/types.h>
 #include <stdio.h>
 #include <unistd.h>
 
-static const size_t size = 100 * (1 << 20); // 100MB
-
 int main() {
 	pid_t pid = getpid();
 	printf("My pid is: %d\n", pid);
 
+	size_t size = ((size_t)1 << (sizeof(size_t) * CHAR_BIT - 1));
+
 	void *p;
 	do {
-		p = mmap(0, size, PROT_READ, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
-	} while (p != MAP_FAILED);
+		do {
+			p = mmap(0, size, PROT_READ, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+		} while (p != MAP_FAILED);
+		
+		size >>= 1;
+	} while (size);
 	printf("Mapped at: %p\n", p);
 
 	getchar();