var projExtent = ol.proj.get('EPSG:3857').getExtent();
    var startResolution = ol.extent.getWidth(projExtent) / 256;
    console.log("startResolution:", startResolution);
    var resolutions = new Array(22);
    for (var i = 0, ii = resolutions.length; i < ii; ++i) {
        resolutions[i] = startResolution / Math.pow(2, i);
    }

  var tileGrid = new ol.tilegrid.TileGrid({
        minZoom: 6,
        extent: [-13884991, 2870341, -7455066, 6338219],
        resolutions: resolutions,
        tileSize: [512, 512]
    });

   var demolayer2 = new ol.layer.Tile({
        source: new ol.source.TileWMS({


           // url: 'http://localhost:8080/geoserver/wms',
            url: 'http://localhost:8080/geoserver/gwc/service/wms',

            params: { 'LAYERS': 'topp:states', 'TILED': true, 'SRS': 'EPSG:3857'},

            serverType: 'geoserver',
            tileGrid: tileGrid

        })
    })

   var view = new ol.View({
            center: ol.proj.transform([-74.0, 40], 'EPSG:4326', 'EPSG:900913'),
            zoom: 7,
            projection: projection,
            extent: [-13884991, 2870341, -7455066, 6338219]
        });

        var map = new ol.Map({
            controls: ol.control.defaults({ attribution: false }).extend([
                new ol.control.MousePosition()

            ]),
            target: 'map',
          //  pixelRatio: 1,
            view: view
        });

        var osm = new ol.layer.Tile({
            source: new ol.source.OSM()
        });

        map.addLayer(osm);
        map.addLayer(demolayer2);