php---读取大文件最后几行

$fp = fopen("./epoll.c", "r");

$lines = 3;

$i = 1;
while (1) {
    fseek($fp, -$i, SEEK_END);
    $tmp = fgetc($fp);
    if (!$lines) break;
    if ($tmp == "
")
    {
        echo fgets($fp);
        --$lines;
    }
    ++$i;
}