intel的超线程技术能让一个物理核上并行执行两个线程，大多数情况下能提高硬件资源的利用率，增强系统性能。对于cpu密集型的数值程序，超线程技术可能会导致整体程序性能下降。鉴于此，执行OpenMP或者MPI数值程序时建议关闭超线程技术。

以下是github上找到的动态打开、关闭超线程技术的脚本。其原理是根据/sys/devices/system/cpu/cpuX/topology/thread_siblings_list文件找到逻辑核的关系，然后编辑/sys/devices/system/cpu/cpuX/online文件实现动态开启和关闭超线程技术。

#!/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 

备注：

1. 脚本需root权限执行；
2. 可以通过cat /proc/cpuinfo查看启用的cpu信息，该命令无需root权限；
3. lscpu命令可查看cpu的状态（无需root权限）：超线程状态下threads per core数值为2，禁用时为1.

参考

1. Disable / Enable HyperThreading cores on runtime – linux

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