问什么是Rss信息?不是Rss xml源

EN

size_t zmalloc_get_rss(void) {
   int page = sysconf(_SC_PAGESIZE);
   size_t rss;
   char buf[4096];
   char filename[256];
   int fd, count;
   char *p, *x;

   snprintf(filename,256,"/proc/%d/stat",getpid());
   if ((fd = open(filename,O_RDONLY)) == -1) return 0;
   if (read(fd,buf,4096) <= 0) {
       close(fd);
       return 0;
   }
   close(fd);

   p = buf;
   count = 23; /* RSS is the 24th field in /proc/<pid>/stat */
   while(p && count--) {
       p = strchr(p,' ');
       if (p) p++;
   }
   if (!p) return 0;
   x = strchr(p,' ');
   if (!x) return 0;
   *x = '\0';

   rss = strtoll(p,NULL,10);
   rss *= page;
   return rss;
}