Add case to test zram data correct

Signed-off-by: Wenchao Hao <haowenchao22@gmail.com>

madvise.c

@@ -0,0 +1,138 @@
+#include <string.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <string.h>
+#include <sys/time.h>
+#include <openssl/md5.h>
+
+#define SIZE 19*1024*1024
+#define PAGE_SIZE 4096          // 4KB
+#define CHUNK_SIZE 8 * 1024     // 8KB
+
+void compute_md5(const unsigned char *data, size_t length, unsigned char *md5_hash) {
+	MD5_CTX md5_ctx;
+
+	MD5_Init(&md5_ctx);
+
+	MD5_Update(&md5_ctx, data, length);
+
+	MD5_Final(md5_hash, &md5_ctx);
+}
+
+void print_md5(unsigned char *md5_hash) {
+	for (int i = 0; i < MD5_DIGEST_LENGTH; i++) {
+		printf("%02x", md5_hash[i]);
+	}
+	printf("\n");
+}
+
+unsigned long long tv_to_ms(struct timeval tv)
+{
+	return tv.tv_sec * 1000 + tv.tv_usec / 1000;
+}
+
+int main()
+{
+	char c;
+	pid_t pid;
+	int i;
+	int j = 0;
+	struct timeval tv_b, tv_e;;
+	unsigned char md5_hash[MD5_DIGEST_LENGTH];
+
+	unsigned long *p = mmap(NULL, SIZE, PROT_READ | PROT_WRITE,
+			MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+	if (!p) {
+		perror("fail to get memory");
+		exit(-1);
+	}
+
+	printf("0x%lx\n", p);
+
+	madvise(p, SIZE, MADV_HUGEPAGE);
+
+	for (j = 0; j < SIZE / 8; j += 8)
+		*(p + j) = j;
+
+	for (size_t offset = PAGE_SIZE; offset < SIZE; offset += CHUNK_SIZE) {
+		char *str = (char *)p + offset;
+
+		sprintf(str, "child");
+	}
+
+	for (size_t offset = PAGE_SIZE; offset < SIZE; offset += CHUNK_SIZE) {
+		compute_md5((unsigned char *)p + offset, PAGE_SIZE, md5_hash);
+		printf("MD5 of the buffer: ");
+		print_md5(md5_hash);
+	}
+
+	gettimeofday(&tv_b, NULL);
+	madvise(p, SIZE, MADV_PAGEOUT);
+	gettimeofday(&tv_e, NULL);
+
+	printf("swp out bandwidth: %ld bytes/ms\n",
+			SIZE/(tv_to_ms(tv_e) - tv_to_ms(tv_b)));
+
+	pid = fork();
+
+	if (pid == 0) {
+		printf("child: freeing some swap\n");
+		for (size_t offset = 0; offset < SIZE; offset += CHUNK_SIZE) {
+			if (madvise((void *)((char *)p + offset), PAGE_SIZE, MADV_DONTNEED) == -1) {
+				perror("madvise failed");
+				return -1;
+			}
+		}
+
+		printf("child: sleep\n");
+		sleep(5);
+
+		printf("child: reading swaped data\n");
+
+		for (size_t offset = PAGE_SIZE; offset < SIZE; offset += CHUNK_SIZE) {
+			char *str = (char *)p + offset;
+
+			if (strcmp(str, "child"))
+				printf("%s\n", str);
+
+		}
+		printf("child: read done\n");
+
+		for (size_t offset = PAGE_SIZE; offset < SIZE; offset += CHUNK_SIZE) {
+			compute_md5((unsigned char *)p + offset, PAGE_SIZE, md5_hash);
+			printf("MD5 of the buffer: ");
+			print_md5(md5_hash);
+		}
+#if 2
+	} else {
+		printf("parent: sleeping\n");
+		sleep(1);
+		printf("parent: unmapping origin memory region\n");
+		munmap(p, SIZE);
+		printf("parent: alloc new memory region\n");
+
+		p = mmap(NULL, 9 * 1024 * 1024, PROT_READ | PROT_WRITE,
+				MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+
+		for (j = 0; j < 1024 * 1024; j+=8)
+			*(p + j) = j + 10;
+
+		for (size_t offset = 0; offset < 8 * 1024 * 1024; offset += CHUNK_SIZE) {
+			char *str = (char *)p + offset + PAGE_SIZE;
+			sprintf(str, "parent");
+		}
+
+		madvise(p, 9 * 1024 * 1024, MADV_PAGEOUT);
+#endif
+	}
+
+	while(1) {
+		sleep(100);
+	}
+
+	return 0;
+}