diff --git a/kernel/Cargo.lock b/kernel/Cargo.lock
index 6761aa42..53679e5c 100644
--- a/kernel/Cargo.lock
+++ b/kernel/Cargo.lock
@@ -196,7 +196,7 @@ dependencies = [
 [[package]]
 name = "isomorphic_drivers"
 version = "0.1.0"
-source = "git+https://github.com/rcore-os/isomorphic_drivers#4a6546922bc5b1255631840f63d6b8b595b39de9"
+source = "git+https://github.com/rcore-os/isomorphic_drivers#642e139b4c4a06a75d9530e9d60a33c514aea060"
 dependencies = [
  "bitflags 1.0.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "spin 0.5.0 (registry+https://github.com/rust-lang/crates.io-index)",
diff --git a/tools/pkttop.sh b/tools/pkttop.sh
new file mode 100755
index 00000000..92060982
--- /dev/null
+++ b/tools/pkttop.sh
@@ -0,0 +1,17 @@
+#!/bin/bash
+# https://www.unixteacher.org/blog/linux/display-packets-per-second-on-linux/
+
+time="1"     # one second
+int="enp3s0f0"   # network interface
+
+while true
+do
+	txpkts_old="`cat /sys/class/net/$int/statistics/tx_packets`" # sent packets
+	rxpkts_old="`cat /sys/class/net/$int/statistics/tx_packets`" # recv packets
+		sleep $time
+	txpkts_new="`cat /sys/class/net/$int/statistics/tx_packets`" # sent packets
+	rxpkts_new="`cat /sys/class/net/$int/statistics/tx_packets`" # recv packets
+	txpkts="`expr $txpkts_new - $txpkts_old`"		     # evaluate expressions for sent packets
+	rxpkts="`expr $rxpkts_new - $rxpkts_old`"		     # evaluate expressions for recv packets
+		echo "tx $txpkts pkts/s - rx $rxpkts pkts/ on interface $int"
+done
diff --git a/user b/user
index fae914b1..4bcc820a 160000
--- a/user
+++ b/user
@@ -1 +1 @@
-Subproject commit fae914b11b8de423d3b11f7259db03cf6cdf3d21
+Subproject commit 4bcc820a8b316c177cc5d82ee5edbbe0ac551814