前言
intel的超線程技術(shù)能讓一個物理核上并行執(zhí)行兩個線程,大多數(shù)情況下能提高硬件資源的利用率,增強系統(tǒng)性能。對于cpu密集型的數(shù)值程序,超線程技術(shù)可能會導(dǎo)致整體程序性能下降。鑒于此,執(zhí)行OpenMP或者MPI數(shù)值程序時建議關(guān)閉超線程技術(shù)。
以下是github上找到的動態(tài)打開、關(guān)閉超線程技術(shù)的腳本。其原理是根據(jù)/sys/devices/system/cpu/cpuX/topology/thread_siblings_list文件找到邏輯核的關(guān)系,然后編輯/sys/devices/system/cpu/cpuX/online文件實現(xiàn)動態(tài)開啟和關(guān)閉超線程技術(shù)。
#!/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
備注:
- 腳本需root權(quán)限執(zhí)行;
- 可以通過cat /proc/cpuinfo查看啟用的cpu信息,該命令無需root權(quán)限;
- lscpu命令可查看cpu的狀態(tài)(無需root權(quán)限):超線程狀態(tài)下threads per core數(shù)值為2,禁用時為1.
參考
Disable / Enable HyperThreading cores on runtime – linux
總結(jié)
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