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--- scripts:hyper-threading [2017/09/03 07:44] – Sean Rhone
+++ scripts:hyper-threading [2017/09/04 06:10] – [Information] Sean Rhone
@@ Line 1: / Line 1: @@
+====== Information ======
+  * Scripts to disable/re-enable Intel's Hyper-threading technology
+  * Similar functionality can be achieved by setting the ''maxcpus'' kernel option to half the amount of presented cores ((a i7-6700HQ has 4 cores, but with HT, it shows 8; so to disable HT, ''maxcpus'' should be ''4'' and the complete option will look like ''maxcpus=4''))
+===== Credit =====
+  * https://serverfault.com/a/797534
+====== Disable HT ======
+  * This disables the virtual cores created by Hyper-threading and leaves the actual cores enabled
+  sudo mkdir -p '/root/Scripts' && sudo -e '/root/Scripts/ht-off.sh' && sudo chmod +x '/root/Scripts/ht-off.sh'
+<code>
+#!/bin/bash
+for CPU in /sys/devices/system/cpu/cpu[0-7]*; 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
+        echo "-> disable (HT core)"
+        echo "0" > $CPU/online
+    fi
+done
+lscpu | grep 'Thread(s) per core'
+lscpu | grep 'On-line CPU(s) list'
+lscpu | grep 'Off-line CPU(s) list'</code>
+  su -c '/root/Scripts/ht-off.sh'
+===== Service =====
+  sudo -e '/etc/systemd/system/ht-off.service' && sudo systemctl daemon-reload && sudo systemctl enable 'ht-off' --now && sudo systemctl status 'ht-off' -l
+<code>
+[Unit]
+Description=Intel Hyper-Threading Disable
+After=basic.target
+Wants=basic.target
+[Service]
+Type=oneshot
+ExecStart='/bin/bash' -c '/root/Scripts/ht-off.sh'
+[Install]
+WantedBy=basic.target</code>
+====== Enable HT ======
+  * This re-enables disabled cores from the above script
+  sudo mkdir -p '/root/Scripts' && sudo -e '/root/Scripts/ht-on.sh' && sudo chmod +x '/root/Scripts/ht-on.sh'
+<code>
+#!/bin/bash
+for CPU in /sys/devices/system/cpu/cpu[0-7]*; 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
+        echo "-> enable (HT core)"
+        echo "1" > $CPU/online
+    fi
+done
+lscpu | grep 'Thread(s) per core'
+lscpu | grep 'On-line CPU(s) list'
+lscpu | grep 'Off-line CPU(s) list'</code>
+  su -c '/root/Scripts/ht-on.sh'