測試代碼

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

int main(int argc, char**argv)
{
        char mode = 'm';
        size_t size = 1024;
        size_t c_size = 0, v_size = 0;
        char * p = NULL;
        int ret;

        while(1) {
                ret = scanf("%c %ld", &mode, &size);
                if(ret != 2) continue;
                printf("action: mode: %c and size: %ld\n", mode, size);
                p = malloc(size*1024*1024);
                if(p == NULL) {
                        perror("malloc failed");
                        continue;
                }
                v_size += size;
                if(mode == 'c') {
                        p = memset(p, 0, size*1024*1024);
                        if(p == NULL) {
                                perror("memset failed\n");
                                continue;
                        }
                        c_size += size;
                }
                printf("rss: %ld v_size: %ld\n", c_size, v_size);
        }
        return 0;
}

測試結(jié)論

1. 單個進程的虛擬地址空間可以超過物理內(nèi)存和swap的總和。
2. malloc 但是未初始化的內(nèi)存僅占用地址空間，memset 后占用 RSS。