increased buffer size in gandalfing

crates/apollo_network_benchmark/run/entrypoint.sh

@@ -62,8 +62,44 @@ apply_shaping() {
   fi
 
   # If latency is set, add netem (delay in ms)
+  # Calculate queue limit to prevent packet drops with large delays
+  # Formula: limit = (expected_throughput_bps * delay_seconds) / (avg_packet_size_bytes * 8)
+  # For safety, we use a generous default: assume 1500 byte packets and calculate for 1 second of buffering
+  # This gives us: (throughput_kbps * 1000 * delay_ms / 1000) / (1500 * 8) = (throughput_kbps * delay_ms) / 12000
   if [ ! -z "${LATENCY}" ]; then
-    tc qdisc add dev $dev parent $netem_parent netem delay ${LATENCY}ms || true
+    if [ ! -z "${THROUGHPUT}" ]; then
+      # Calculate limit based on throughput and latency
+      # Throughput is in KB/s, latency in ms
+      # Buffer for at least 2x the delay to handle bursts
+      PACKET_SIZE=1500  # bytes
+      BUFFER_MULTIPLIER=2
+      LIMIT=$(( (THROUGHPUT * 1000 * LATENCY * BUFFER_MULTIPLIER) / (PACKET_SIZE * 8) ))
+      # Ensure minimum limit of 1000 packets
+      if [ $LIMIT -lt 1000 ]; then
+        LIMIT=1000
+      fi
+      # Cap at reasonable maximum (100k packets) to avoid excessive memory usage
+      if [ $LIMIT -gt 100000 ]; then
+        LIMIT=100000
+      fi
+      tc qdisc add dev $dev parent $netem_parent netem delay ${LATENCY}ms limit ${LIMIT} || true
+      echo "Applied netem delay ${LATENCY}ms with queue limit ${LIMIT} packets"
+    else
+      # No throughput limit, use a generous default based on latency alone
+      # Assume we might need to buffer packets arriving at 100 Mbps for the delay duration
+      PACKET_SIZE=1500
+      ASSUMED_RATE_MBPS=100
+      BUFFER_MULTIPLIER=2
+      LIMIT=$(( (ASSUMED_RATE_MBPS * 1000 * 1000 * LATENCY * BUFFER_MULTIPLIER) / (1000 * PACKET_SIZE * 8) ))
+      if [ $LIMIT -lt 1000 ]; then
+        LIMIT=1000
+      fi
+      if [ $LIMIT -gt 100000 ]; then
+        LIMIT=100000
+      fi
+      tc qdisc add dev $dev parent $netem_parent netem delay ${LATENCY}ms limit ${LIMIT} || true
+      echo "Applied netem delay ${LATENCY}ms with queue limit ${LIMIT} packets (default calculation)"
+    fi
   fi
 }