perf(quickemu): tune TCG translation cache and enable multithreaded TCG

- Add TCG-specific runtime optimisations in vm_boot for
cross-architecture VMs
- Detect host RAM and set tb-size to 512 for hosts with >=16GB,
otherwise 256
- Append -accel tcg,tb-size=${TCG_TB_SIZE},thread=multi to QEMU args
- Improve TCG translation cache behaviour and SMP performance for TCG
guests

Signed-off-by: Martin Wimpress <martin@wimpress.org>

Author: flexiondotorg

quickemu

@@ -1666,6 +1666,26 @@ function vm_boot() {
             -pidfile "${VMDIR}/${VMNAME}.pid")
     fi
 
+    # TCG-specific optimisations for cross-architecture emulation
+    # Increases translation block cache size to reduce re-translation overhead
+    # and enables multi-threaded TCG for better SMP performance
+    if [ "${QEMU_ACCEL}" == "tcg" ]; then
+        local HOST_RAM_GB=0
+        if [ "${OS_KERNEL}" == "Darwin" ]; then
+            HOST_RAM_GB=$(($(sysctl -n hw.memsize) / (1024*1024*1024)))
+        else
+            HOST_RAM_GB=$(awk '/MemTotal/ {printf "%.0f", $2/1024/1024}' /proc/meminfo)
+        fi
+        # Use larger translation cache on hosts with 16GB+ RAM
+        if [ "${HOST_RAM_GB}" -ge 16 ]; then
+            TCG_TB_SIZE=512
+        else
+            TCG_TB_SIZE=256
+        fi
+        # shellcheck disable=SC2054,SC2206
+        args+=(-accel tcg,tb-size=${TCG_TB_SIZE},thread=multi)
+    fi
+
     if [ "${guest_os}" == "windows" ] || [ "${guest_os}" == "windows-server" ] || [ "${guest_os}" == "reactos" ] || [ "${guest_os}" == "freedos" ]; then
         # shellcheck disable=SC2054
         args+=(-rtc base=localtime,clock=host,driftfix=slew)