[PATCH for vm-scalability] usemem: Add code for touch-alloc

[Hui Zhu]

Add code for touch-alloc.
And Change read memory to write memory to avoid use the zero-page for
reads in do_anonymous_page.

Signed-off-by: Hui Zhu <teawa...@gmail.com>
---
 usemem.c | 34 ++++++++++++++++++++++------------
 1 file changed, 22 insertions(+), 12 deletions(-)

diff --git a/usemem.c b/usemem.c
index e2c46ec..5b90aae 100644
--- a/usemem.c
+++ b/usemem.c
@@ -329,6 +329,18 @@ void detach(void)
        }
 }
 
+unsigned long do_access(unsigned long *p, unsigned long idx, int read)
+{
+       volatile unsigned long *vp = p;
+
+       if (read)
+               return vp[idx]; /* read data */
+       else {
+               vp[idx] = idx;  /* write data */
+               return 0;
+       }
+}
+
 unsigned long * allocate(unsigned long bytes)
 {
        unsigned long *p;
@@ -355,6 +367,14 @@ unsigned long * allocate(unsigned long bytes)
                p = (unsigned long *)ALIGN((unsigned long)p, pagesize - 1);
        }
 
+       if (opt_touch_alloc) {
+               unsigned long i;
+               unsigned long m = bytes / sizeof(*p);
+
+               for (i = 0; i < m; i += 1)
+                       do_access(p, i, 0);
+       }
+
        return p;
 }
 
@@ -436,18 +456,6 @@ void shm_unlock(int seg_id)
        shmctl(seg_id, SHM_UNLOCK, NULL);
 }
 
-unsigned long do_access(unsigned long *p, unsigned long idx, int read)
-{
-       volatile unsigned long *vp = p;
-
-       if (read)
-               return vp[idx]; /* read data */
-       else {
-               vp[idx] = idx;  /* write data */
-               return 0;
-       }
-}
-
 #define NSEC_PER_SEC  (1UL * 1000 * 1000 * 1000)
 
 long nsec_sub(long nsec1, long nsec2)
@@ -953,6 +961,8 @@ int main(int argc, char *argv[])
                                opt_punch_holes = 1;
                        } else if (strcmp(opts[opt_index].name, "init-time") == 
0) {
                                opt_init_time = 1;
+                       } else if (strcmp(opts[opt_index].name, "touch-alloc") 
== 0) {
+                               opt_touch_alloc = 1;
                        } else
                                usage(1);
                        break;
-- 
2.17.1