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Jose Ricardo Zivianityreld
Jose Ricardo Ziviani
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tyreld
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Add smtstate script to persist SMT changes
This patch introduces smtstate script responsible to save and restore the current SMT state into /var/lib/powerpc-utils/smt.state. Signed-off-by: Jose Ricardo Ziviani <[email protected]> Signed-off-by: Tyrel Datwyler <[email protected]>
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‎man/smtstate.8

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.\"
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.\" Copyright (C) 2020 International Business Machines
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.\"
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.TH SMTSTATE 8 "January 2020" Linux "Linux on Power Service Tools"
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.SH NAME
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smtstate \- Save and restore the current SMT state
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.SH SYNOPSIS
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.B /usr/sbin/smtstate [ option ]
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.SH DESCRIPTION
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The
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.I smtstate
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script is used to persist the current SMT state and to restore it at a convenient time. The idea behind it is to use the script together with a systemd service to save SMT state at any shutdown event and to restore it at an early stage of the boot process. Such implementation creates a way to persist the SMT state across reboots, without requiring any other configuration from system administrators.
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.SH OPTIONS
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.TP
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\fB\-\-save\fR
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Save the value read from "ppc64_cpu --smt -n" into the state file stored at /var/lib/powerpc-utils/.
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.TP
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\fB\-\-load\fR
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Read the saved SMT value from the state file stored at /var/lib/powerpc-utils/ and set "ppc64_cpu --smt=value".
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.TP
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\fB\-\-help\fR
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Display a concise command usage statement.
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.SH AUTHOR
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Written by Jose Ricardo Ziviani

‎scripts/smtstate.in

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#!/bin/bash
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# Copyright (c) 2020 International Business Machines
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#
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# This program is free software; you can redistribute it and/or
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# modify it under the terms of the GNU General Public License
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# as published by the Free Software Foundation; either version 2
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# of the License, or (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program; if not, write to the Free Software
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# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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# Simple script designed to save and restore the SMT state.
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readonly SMT_STATE=/var/lib/powerpc-utils/smt.state
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readonly SMT_STATE_BKP=/tmp/smt.state.backup
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readonly PPC64CPU=@sbindir@/ppc64_cpu
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update_state() {
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# sanity check
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smt_state_exist
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# users can online and offline individual CPUs, creating an inconsistent
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# SMT state. In this case ppc64_cpu --smt displays a more complex
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# configuration, such case is beyond the scope here so we simply ignore it
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if [ $($PPC64CPU --smt -n | cut -d= -f2 | grep ^[1-8]$ > /dev/null; echo $?) -ne 0 ]
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then
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return
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fi
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# create a temporary backup
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cp -p $SMT_STATE $SMT_STATE_BKP
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if [ $? -ne 0 ]
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then
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logger -t ${0##*/}[$$] "Error saving $SMT_STATE_BKP"
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exit 1
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fi
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# update SMT state file
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local current_smt=$($PPC64CPU --smt -n | cut -d= -f2)
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sed -i "s/SMT_VALUE=[0-9]/SMT_VALUE=$current_smt/" $SMT_STATE
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if [ $? -ne 0 ]
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then
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logger -t ${0##*/}[$$] "Error updating $SMT_STATE"
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cp -p $SMT_STATE_BKP $SMT_STATE
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rm $SMT_STATE_BKP
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exit 1
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fi
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rm $SMT_STATE_BKP
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}
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set_smt() {
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# sanity check
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smt_state_exist
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# get saved SMT value and set it
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local smt=$(grep "^SMT_VALUE=[1-8]$" $SMT_STATE | cut -d= -f2)
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if [ "$smt" -lt 1 ] || [ "$smt" -gt 8 ]
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then
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logger -t ${0##*/}[$$] "$smt is an invalid SMT state"
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exit 1
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fi
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$PPC64CPU --smt="$smt"
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if [ $? -ne 0 ]
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then
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logger -t ${0##*/}[$$] "Error updating SMT=$smt"
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exit 1
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fi
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}
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smt_state_exist() {
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if [ ! -f $SMT_STATE ]
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then
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logger -t ${0##*/}[$$] "$SMT_STATE not found"
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exit 1
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fi
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grep "^SMT_VALUE=[1-8]$" $SMT_STATE > /dev/null 2>&1
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if [ $? -ne 0 ]
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then
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logger -t ${0##*/}[$$] "$SMT_STATE does not have SMT_VALUE defined"
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exit 1
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fi
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}
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check_smt_capable() {
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local msg=$($PPC64CPU --smt 2>&1 | grep -q "Machine is not SMT capable"; echo $?)
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if [ "$msg" -eq 0 ]
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then
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logger -t ${0##*/}[$$] "Machine is not SMT capable, exiting"
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exit 0
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fi
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}
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usage() {
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printf "$0 is a script designed to save/restore the SMT state.\n"
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printf "Usage: %s [--save | --load | --help]\n" "$0"
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printf "\t--save (default): save current SMT state\n"
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printf "\t--load : set SMT to the value stored\n"
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printf "\t--help : print this message\n"
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printf "SMT state is saved in $SMT_STATE\n"
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}
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main() {
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# if machine is not SMT capable don't even bother to continue
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check_smt_capable
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local action="$1"
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case "$action" in
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--load)
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set_smt
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;;
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--save)
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update_state
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;;
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--help)
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usage
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;;
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*)
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logger -s -t ${0##*/}[$$] "Invalid action $1"
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usage
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exit 1
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;;
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esac
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}
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action=${1:---save}
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main "$action"

‎var/lib/powerpc-utils/smt.state

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# smt.state configures the SMT default value for next
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# boots.
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# SMT state. If smt_init.service is enabled, this value will be
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# used to set SMT in the next boot. If smtd.service is enabled,
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# this value will be updated whenever ppc64_cpu --smt=<value>
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# is issued.
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SMT_VALUE=1

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