feat: better blocksize heuristics (#3748)

etc/grafana/dashboards/overview.json

@@ -2643,6 +2643,143 @@
       "title": "Downloader buffer",
       "type": "timeseries"
     },
+    {
+      "datasource": {
+        "type": "prometheus",
+        "uid": "${DS_PROMETHEUS}"
+      },
+      "description": "The number of blocks in a request and size in bytes of those block responses",
+      "fieldConfig": {
+        "defaults": {
+          "custom": {
+            "drawStyle": "line",
+            "lineInterpolation": "linear",
+            "barAlignment": 0,
+            "lineWidth": 1,
+            "fillOpacity": 0,
+            "gradientMode": "none",
+            "spanNulls": false,
+            "showPoints": "auto",
+            "pointSize": 5,
+            "stacking": {
+              "mode": "none",
+              "group": "A"
+            },
+            "axisPlacement": "auto",
+            "axisLabel": "",
+            "axisColorMode": "text",
+            "scaleDistribution": {
+              "type": "linear"
+            },
+            "axisCenteredZero": false,
+            "hideFrom": {
+              "tooltip": false,
+              "viz": false,
+              "legend": false
+            },
+            "thresholdsStyle": {
+              "mode": "off"
+            }
+          },
+          "color": {
+            "mode": "palette-classic"
+          },
+          "mappings": [],
+          "thresholds": {
+            "mode": "absolute",
+            "steps": [
+              {
+                "color": "green",
+                "value": null
+              },
+              {
+                "color": "red",
+                "value": 80
+              }
+            ]
+          },
+          "unit": "bytes"
+        },
+        "overrides": [
+          {
+            "matcher": {
+              "id": "byFrameRefID",
+              "options": "B"
+            },
+            "properties": [
+              {
+                "id": "custom.axisPlacement",
+                "value": "right"
+              },
+              {
+                "id": "unit",
+                "value": "blocks"
+              }
+            ]
+          }
+        ]
+      },
+      "gridPos": {
+        "h": 8,
+        "w": 12,
+        "x": 5,
+        "y": 110
+      },
+      "id": 102,
+      "options": {
+        "tooltip": {
+          "mode": "multi",
+          "sort": "none"
+        },
+        "legend": {
+          "showLegend": true,
+          "displayMode": "list",
+          "placement": "bottom",
+          "calcs": []
+        }
+      },
+      "targets": [
+        {
+          "datasource": {
+            "type": "prometheus",
+            "uid": "Prometheus"
+          },
+          "editorMode": "builder",
+          "expr": "reth_downloaders_bodies_response_response_size_bytes{instance=~\"$instance\"}",
+          "hide": false,
+          "legendFormat": "Response size",
+          "range": true,
+          "refId": "A"
+        },
+        {
+          "datasource": {
+            "type": "prometheus",
+            "uid": "Prometheus"
+          },
+          "editorMode": "builder",
+          "expr": "reth_downloaders_bodies_response_response_length{instance=~\"$instance\"}",
+          "hide": false,
+          "legendFormat": "Individual response length",
+          "range": true,
+          "refId": "B"
+        },
+        {
+          "datasource": {
+            "type": "prometheus",
+            "uid": "${DS_PROMETHEUS}"
+          },
+          "editorMode": "builder",
+          "expr": "reth_downloaders_bodies_response_response_size_bytes / reth_downloaders_bodies_response_response_length",
+          "hide": false,
+          "instant": false,
+          "legendFormat": "Mean body size in response",
+          "range": true,
+          "refId": "C"
+        }
+      ],
+      "title": "Block body response sizes",
+      "type": "timeseries"
+    },
     {
       "collapsed": false,
       "gridPos": {