1 files changed, 11 insertions, 2 deletions

diff --git a/usr.bin/cmp/regular.c b/usr.bin/cmp/regular.c
index e791522a99be..f540ab4aebe8 100644
--- a/usr.bin/cmp/regular.c
+++ b/usr.bin/cmp/regular.c
@@ -71,18 +71,27 @@ c_regular(fd1, file1, skip1, len1, fd2, file2, skip2, len2)
 		eofmsg(file2);
 	len2 -= skip2;
 
+	pagemask = (off_t)getpagesize() - 1;
+	off1 = ROUNDPAGE(skip1);
+	off2 = ROUNDPAGE(skip2);
+
 	length = MIN(len1, len2);
 	if (length > SIZE_T_MAX)
 		return (c_special(fd1, file1, skip1, fd2, file2, skip2));
 
 	if ((p1 = (u_char *)mmap(NULL,
-	    (size_t)length, PROT_READ, 0, fd1, skip1)) == (u_char *)-1)
+	    (size_t)length, PROT_READ, MAP_SHARED, fd1, off1)) == (u_char *)MAP_FAILED)
 		err(ERR_EXIT, "%s", file1);
+
+	madvise(p1, length, MADV_SEQUENTIAL);
 	if ((p2 = (u_char *)mmap(NULL,
-	    (size_t)length, PROT_READ, 0, fd2, skip2)) == (u_char *)-1)
+	    (size_t)length, PROT_READ, MAP_SHARED, fd2, off2)) == (u_char *)MAP_FAILED)
 		err(ERR_EXIT, "%s", file2);
+	madvise(p2, length, MADV_SEQUENTIAL);
 
 	dfound = 0;
+	p1 += skip1 - off1;
+	p2 += skip2 - off2;
 	for (byte = line = 1; length--; ++p1, ++p2, ++byte) {
 		if ((ch = *p1) != *p2)
 			if (lflag) {