Nginx开启gzip无效

Question

    gzip on;
    gzip_static on;
    gzip_min_length 256;
    gzip_comp_level 6;
    gzip_types text/plain application/x-javascript application/javascript text/javascript text/xml text/css;
    gzip_vary on;
    gzip_disable "MSIE [1-6]\.";
    gzip_buffers 16 8k;
    gzip_http_version 1.1;