Linux關閉超線程

Intel的超線程技術能讓一個物理核上並行執行兩個線程，大多數情況下能提高硬件資源的利用率，增強系統性能。對於cpu密集型的數值程序，超線程技術可能會導致整體程序性能下降. 鑒於此，執行OpenMP或者MPI數值程序時建議關閉超線程技術.

以下是github上找到的動態打開、關閉超線程技術的腳本. 其原理是根據/sys/devices/system/cpu/cpuX/topology/thread_siblings_list文件找到邏輯核的關系，然后編輯/sys/devices/system/cpu/cpuX/online文件實現動態開啟和關閉超線程技術.

#!/bin/bash

HYPERTHREADING=1

function toggleHyperThreading() {
  for CPU in /sys/devices/system/cpu/cpu[0-9]*; do
      CPUID=`basename $CPU | cut -b4-`
      echo -en "CPU: $CPUID\t"
      [ -e $CPU/online ] && echo "1" > $CPU/online
      THREAD1=`cat $CPU/topology/thread_siblings_list | cut -f1 -d,`
      if [ $CPUID = $THREAD1 ]; then
          echo "-> enable"
          [ -e $CPU/online ] && echo "1" > $CPU/online
      else
        if [ "$HYPERTHREADING" -eq "0" ]; then echo "-> disabled"; else echo "-> enabled"; fi
          echo "$HYPERTHREADING" > $CPU/online
      fi
  done
}

function enabled() {
        echo -en "Enabling HyperThreading\n"
        HYPERTHREADING=1
        toggleHyperThreading
}

function disabled() {
        echo -en "Disabling HyperThreading\n"
        HYPERTHREADING=0
        toggleHyperThreading
}

#
ONLINE=$(cat /sys/devices/system/cpu/online)
OFFLINE=$(cat /sys/devices/system/cpu/offline)
echo "---------------------------------------------------"
echo -en "CPU's online: $ONLINE\t CPU's offline: $OFFLINE\n"
echo "---------------------------------------------------"
while true; do
    read -p "Type in e to enable or d disable hyperThreading or q to quit [e/d/q] ?" ed
    case $ed in
        [Ee]* ) enabled; break;;
        [Dd]* ) disabled;exit;;
        [Qq]* ) exit;;
        * ) echo "Please answer e for enable or d for disable hyperThreading.";;
    esac
done

• 腳本需要root執行
• 完成后用lscpu查看Thread(s) per core是否為1

參考：

轉載請注明原文出處：https://tlanyan.me/linux-enab...

source script: https://gist.github.com/samueljon/e7818edeb218f5e2f1e3e258949d04c8

---

2020/05/30更新

以上似乎對集群scheduler PBS不起作用，建議還是在BIOS中關閉！