diff --git a/test/benchmark/iperf3/tcp_virtio_bw/host.sh b/test/benchmark/iperf3/tcp_virtio_bw/host.sh
index 9c61a2fb8..5f8912bfb 100755
--- a/test/benchmark/iperf3/tcp_virtio_bw/host.sh
+++ b/test/benchmark/iperf3/tcp_virtio_bw/host.sh
@@ -7,7 +7,8 @@ set -e
 # Function to stop the guest VM
 stop_guest() {
     echo "Stopping guest VM..."
-    pgrep qemu | xargs kill
+    # `-r` means if there's no qemu, the kill won't be executed
+    pgrep qemu | xargs -r kill
 }
 
 # Trap EXIT signal to ensure guest VM is stopped on script exit
diff --git a/test/benchmark/memcached/t16_conc64_window10k/host.sh b/test/benchmark/memcached/t16_conc64_window10k/host.sh
index 681eb92d2..7caf45af6 100644
--- a/test/benchmark/memcached/t16_conc64_window10k/host.sh
+++ b/test/benchmark/memcached/t16_conc64_window10k/host.sh
@@ -7,7 +7,8 @@ set -e
 # Function to stop the guest VM
 stop_guest() {
     echo "Stopping guest VM..."
-    pgrep qemu | xargs kill
+    # `-r` means if there's no qemu, the kill won't be executed
+    pgrep qemu | xargs -r kill
 }
 
 # Trap EXIT signal to ensure guest VM is stopped on script exit
diff --git a/test/benchmark/memcached/t8_conc32_window10k/host.sh b/test/benchmark/memcached/t8_conc32_window10k/host.sh
index dab790354..411d5aeab 100644
--- a/test/benchmark/memcached/t8_conc32_window10k/host.sh
+++ b/test/benchmark/memcached/t8_conc32_window10k/host.sh
@@ -7,7 +7,8 @@ set -e
 # Function to stop the guest VM
 stop_guest() {
     echo "Stopping guest VM..."
-    pgrep qemu | xargs kill
+    # `-r` means if there's no qemu, the kill won't be executed
+    pgrep qemu | xargs -r kill
 }
 
 # Trap EXIT signal to ensure guest VM is stopped on script exit
diff --git a/test/benchmark/memcached/t8_conc32_window20k/host.sh b/test/benchmark/memcached/t8_conc32_window20k/host.sh
index 9aa37551b..9cd6262b9 100644
--- a/test/benchmark/memcached/t8_conc32_window20k/host.sh
+++ b/test/benchmark/memcached/t8_conc32_window20k/host.sh
@@ -7,7 +7,8 @@ set -e
 # Function to stop the guest VM
 stop_guest() {
     echo "Stopping guest VM..."
-    pgrep qemu | xargs kill
+    # `-r` means if there's no qemu, the kill won't be executed
+    pgrep qemu | xargs -r kill
 }
 
 # Trap EXIT signal to ensure guest VM is stopped on script exit
diff --git a/test/benchmark/nginx/http_file16KB_bw/host.sh b/test/benchmark/nginx/http_file16KB_bw/host.sh
index ff6d44284..74ece7904 100644
--- a/test/benchmark/nginx/http_file16KB_bw/host.sh
+++ b/test/benchmark/nginx/http_file16KB_bw/host.sh
@@ -7,7 +7,8 @@ set -e
 # Function to stop the guest VM
 stop_guest() {
     echo "Stopping guest VM..."
-    pgrep qemu | xargs kill
+    # `-r` means if there's no qemu, the kill won't be executed
+    pgrep qemu | xargs -r kill
 }
 
 # Trap EXIT signal to ensure guest VM is stopped on script exit
diff --git a/test/benchmark/nginx/http_file32KB_bw/host.sh b/test/benchmark/nginx/http_file32KB_bw/host.sh
index aabd10e54..e595922ca 100644
--- a/test/benchmark/nginx/http_file32KB_bw/host.sh
+++ b/test/benchmark/nginx/http_file32KB_bw/host.sh
@@ -7,7 +7,8 @@ set -e
 # Function to stop the guest VM
 stop_guest() {
     echo "Stopping guest VM..."
-    pgrep qemu | xargs kill
+    # `-r` means if there's no qemu, the kill won't be executed
+    pgrep qemu | xargs -r kill
 }
 
 # Trap EXIT signal to ensure guest VM is stopped on script exit
diff --git a/test/benchmark/nginx/http_file4KB_bw/host.sh b/test/benchmark/nginx/http_file4KB_bw/host.sh
index 7cf609bd2..1f0540621 100644
--- a/test/benchmark/nginx/http_file4KB_bw/host.sh
+++ b/test/benchmark/nginx/http_file4KB_bw/host.sh
@@ -7,7 +7,8 @@ set -e
 # Function to stop the guest VM
 stop_guest() {
     echo "Stopping guest VM..."
-    pgrep qemu | xargs kill
+    # `-r` means if there's no qemu, the kill won't be executed
+    pgrep qemu | xargs -r kill
 }
 
 # Trap EXIT signal to ensure guest VM is stopped on script exit
diff --git a/test/benchmark/nginx/http_file64KB_bw/host.sh b/test/benchmark/nginx/http_file64KB_bw/host.sh
index ec9e945ec..a629162b2 100644
--- a/test/benchmark/nginx/http_file64KB_bw/host.sh
+++ b/test/benchmark/nginx/http_file64KB_bw/host.sh
@@ -7,7 +7,8 @@ set -e
 # Function to stop the guest VM
 stop_guest() {
     echo "Stopping guest VM..."
-    pgrep qemu | xargs kill
+    # `-r` means if there's no qemu, the kill won't be executed
+    pgrep qemu | xargs -r kill
 }
 
 # Trap EXIT signal to ensure guest VM is stopped on script exit
diff --git a/test/benchmark/nginx/http_file8KB_bw/host.sh b/test/benchmark/nginx/http_file8KB_bw/host.sh
index 5417bba86..a1c713a79 100644
--- a/test/benchmark/nginx/http_file8KB_bw/host.sh
+++ b/test/benchmark/nginx/http_file8KB_bw/host.sh
@@ -7,7 +7,8 @@ set -e
 # Function to stop the guest VM
 stop_guest() {
     echo "Stopping guest VM..."
-    pgrep qemu | xargs kill
+    # `-r` means if there's no qemu, the kill won't be executed
+    pgrep qemu | xargs -r kill
 }
 
 # Trap EXIT signal to ensure guest VM is stopped on script exit
diff --git a/test/benchmark/nginx/http_req10k_conc1_bw/host.sh b/test/benchmark/nginx/http_req10k_conc1_bw/host.sh
index f5bd38036..19fbd55b8 100755
--- a/test/benchmark/nginx/http_req10k_conc1_bw/host.sh
+++ b/test/benchmark/nginx/http_req10k_conc1_bw/host.sh
@@ -7,7 +7,8 @@ set -e
 # Function to stop the guest VM
 stop_guest() {
     echo "Stopping guest VM..."
-    pgrep qemu | xargs kill
+    # `-r` means if there's no qemu, the kill won't be executed
+    pgrep qemu | xargs -r kill
 }
 
 # Trap EXIT signal to ensure guest VM is stopped on script exit
diff --git a/test/benchmark/nginx/http_req10k_conc20_bw/host.sh b/test/benchmark/nginx/http_req10k_conc20_bw/host.sh
index a3a7de672..2d81bbc4c 100755
--- a/test/benchmark/nginx/http_req10k_conc20_bw/host.sh
+++ b/test/benchmark/nginx/http_req10k_conc20_bw/host.sh
@@ -7,7 +7,8 @@ set -e
 # Function to stop the guest VM
 stop_guest() {
     echo "Stopping guest VM..."
-    pgrep qemu | xargs kill
+    # `-r` means if there's no qemu, the kill won't be executed
+    pgrep qemu | xargs -r kill
 }
 
 # Trap EXIT signal to ensure guest VM is stopped on script exit
diff --git a/test/benchmark/redis/get_100k_conc20_rps/host.sh b/test/benchmark/redis/get_100k_conc20_rps/host.sh
index 753aab375..32eb3cb81 100755
--- a/test/benchmark/redis/get_100k_conc20_rps/host.sh
+++ b/test/benchmark/redis/get_100k_conc20_rps/host.sh
@@ -7,7 +7,8 @@ set -e
 # Function to stop the guest VM
 stop_guest() {
     echo "Stopping guest VM..."
-    pgrep qemu | xargs kill
+    # `-r` means if there's no qemu, the kill won't be executed
+    pgrep qemu | xargs -r kill
 }
 
 # Trap EXIT signal to ensure guest VM is stopped on script exit
diff --git a/test/benchmark/redis/ping_inline_100k_conc20_rps/host.sh b/test/benchmark/redis/ping_inline_100k_conc20_rps/host.sh
index 4e2d124e6..b67b74999 100755
--- a/test/benchmark/redis/ping_inline_100k_conc20_rps/host.sh
+++ b/test/benchmark/redis/ping_inline_100k_conc20_rps/host.sh
@@ -7,7 +7,8 @@ set -e
 # Function to stop the guest VM
 stop_guest() {
     echo "Stopping guest VM..."
-    pgrep qemu | xargs kill
+    # `-r` means if there's no qemu, the kill won't be executed
+    pgrep qemu | xargs -r kill
 }
 
 # Trap EXIT signal to ensure guest VM is stopped on script exit
diff --git a/test/benchmark/redis/ping_mbulk_100k_conc20_rps/host.sh b/test/benchmark/redis/ping_mbulk_100k_conc20_rps/host.sh
index af6513780..a8c7d9a1d 100755
--- a/test/benchmark/redis/ping_mbulk_100k_conc20_rps/host.sh
+++ b/test/benchmark/redis/ping_mbulk_100k_conc20_rps/host.sh
@@ -7,7 +7,8 @@ set -e
 # Function to stop the guest VM
 stop_guest() {
     echo "Stopping guest VM..."
-    pgrep qemu | xargs kill
+    # `-r` means if there's no qemu, the kill won't be executed
+    pgrep qemu | xargs -r kill
 }
 
 # Trap EXIT signal to ensure guest VM is stopped on script exit
diff --git a/test/benchmark/redis/set_100k_conc20_rps/host.sh b/test/benchmark/redis/set_100k_conc20_rps/host.sh
index 84f5878c7..e0a83410d 100755
--- a/test/benchmark/redis/set_100k_conc20_rps/host.sh
+++ b/test/benchmark/redis/set_100k_conc20_rps/host.sh
@@ -7,7 +7,8 @@ set -e
 # Function to stop the guest VM
 stop_guest() {
     echo "Stopping guest VM..."
-    pgrep qemu | xargs kill
+    # `-r` means if there's no qemu, the kill won't be executed
+    pgrep qemu | xargs -r kill
 }
 
 # Trap EXIT signal to ensure guest VM is stopped on script exit