[PATCH] usemem: Add option touch-alloc
From: Hui Zhu
Date: Thu Dec 17 2020 - 02:28:40 EST
Some environment will not fault in memory even if MAP_POPULATE is set.
This commit add option touch-alloc to read memory after allocate it to
make sure the pages is fault in.
Signed-off-by: Hui Zhu <teawaterz@xxxxxxxxxxxxxxxxx>
---
usemem.c | 37 +++++++++++++++++++++++++------------
1 file changed, 25 insertions(+), 12 deletions(-)
diff --git a/usemem.c b/usemem.c
index 6d1d575..d93691b 100644
--- a/usemem.c
+++ b/usemem.c
@@ -97,6 +97,7 @@ unsigned long opt_delay = 0;
int opt_read_again = 0;
int opt_punch_holes = 0;
int opt_init_time = 0;
+int opt_touch_alloc = 0;
int nr_task;
int nr_thread;
int nr_cpu;
@@ -157,6 +158,7 @@ void usage(int ok)
" -Z|--read-again read memory again after access the memory\n"
" --punch-holes free every other page after allocation\n"
" --init-time remove the initialization time from the run time and show the initialization time\n"
+ " --touch-alloc read memory after allocate it\n"
" -h|--help show this message\n"
, ourname);
@@ -197,6 +199,7 @@ static const struct option opts[] = {
{ "read-again" , 0, NULL, 'Z' },
{ "punch-holes" , 0, NULL, 0 },
{ "init-time" , 0, NULL, 0 },
+ { "touch-alloc" , 0, NULL, 0 },
{ "help" , 0, NULL, 'h' },
{ NULL , 0, NULL, 0 }
};
@@ -326,6 +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;
@@ -352,6 +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, 1);
+ }
+
return p;
}
@@ -433,18 +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)
@@ -950,6 +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