4790e570ce
As noted in the bugzilla ticket https://bugzilla.redhat.com/show_bug.cgi?id=1554851 The QEMU I/O thread can interrupt the time measurement of the timer. To avoid this problem, only pin the vCPU thread. Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> Reviewed-and-Tested-by: Luiz Capitulino <lcapitulino@redhat.com> v2: - Use unix sockets (Luiz) - Proper numeric output (Luiz)
123 lines
3.5 KiB
Bash
Executable file
123 lines
3.5 KiB
Bash
Executable file
#!/bin/sh
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. /usr/lib/tuned/functions
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CACHE_VALUE_FILE=./lapic_timer_adv_ns
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CACHE_CPU_FILE=./lapic_timer_adv_ns.cpumodel
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KVM_LAPIC_FILE=/sys/module/kvm/parameters/lapic_timer_advance_ns
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QEMU=$(type -P qemu-kvm || echo /usr/libexec/qemu-kvm)
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TSCDEADLINE_LATENCY="/usr/share/qemu-kvm/tscdeadline_latency.flat"
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if [ ! -f "$TSCDEADLINE_LATENCY" ]; then
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TSCDEADLINE_LATENCY="/usr/share/tuned/tscdeadline_latency.flat"
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fi
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run_tsc_deadline_latency()
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{
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dir=`mktemp -d`
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for i in `seq 1000 500 7000`; do
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echo $i > $KVM_LAPIC_FILE
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unixpath=`mktemp`
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chrt -f 1 $QEMU -S -enable-kvm -device pc-testdev \
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-device isa-debug-exit,iobase=0xf4,iosize=0x4 \
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-display none -serial stdio -device pci-testdev \
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-kernel "$TSCDEADLINE_LATENCY" \
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-cpu host \
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-mon chardev=char0,mode=readline \
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-chardev socket,id=char0,nowait,path=$unixpath,server | grep latency | cut -f 2 -d ":" > $dir/out &
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sleep 1s
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pidofvcpu=`echo "info cpus" | nc -U $unixpath | grep thread_id | cut -f 3 -d "=" | tr -d "\r"`
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taskset -p -c $1 $pidofvcpu >/dev/null
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echo "cont" | nc -U $unixpath >/dev/null
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wait
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if [ ! -f $dir/out ]; then
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die running $TSCDEADLINE_LATENCY failed
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fi
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tmp=$(wc -l $dir/out | awk '{ print $1 }')
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if [ $tmp -eq 0 ]; then
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die running $TSCDEADLINE_LATENCY failed
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fi
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A=0
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while read l; do
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A=$(($A+$l))
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done < $dir/out
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lines=`wc -l $dir/out | cut -f 1 -d " "`
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ans=$(($A/$lines))
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echo $i: $ans
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done
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}
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start() {
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setup_kvm_mod_low_latency
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disable_ksm
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# If CPU model has changed, clean the cache
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if [ -f $CACHE_CPU_FILE ]; then
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curmodel=`cat /proc/cpuinfo | grep "model name" | cut -f 2 -d ":" | uniq`
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if [ -z "$curmodel" ]; then
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die failed to read CPU model
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fi
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genmodel=`cat $CACHE_CPU_FILE`
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if [ "$curmodel" != "$genmodel" ]; then
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rm -f $CACHE_VALUE_FILE
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rm -f $CACHE_CPU_FILE
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fi
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fi
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# If the cache is empty, find the best lapic_timer_advance_ns value
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# and cache it
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if [ ! -f $KVM_LAPIC_FILE ]; then
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die $KVM_LAPIC_FILE not found
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fi
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if [ ! -f $CACHE_VALUE_FILE ]; then
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if [ -f "$TSCDEADLINE_LATENCY" ]; then
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tempdir=`mktemp -d`
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isolatedcpu=`echo "$TUNED_isolated_cores_expanded" | cut -f 1 -d ","`
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run_tsc_deadline_latency $isolatedcpu > $tempdir/lat.out
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if ! ./find-lapictscdeadline-optimal.sh $tempdir/lat.out > $tempdir/opt.out; then
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die could not find optimal latency
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fi
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echo `cat $tempdir/opt.out | cut -f 2 -d ":"` > $CACHE_VALUE_FILE
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curmodel=`cat /proc/cpuinfo | grep "model name" | cut -f 2 -d ":" | uniq`
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echo "$curmodel" > $CACHE_CPU_FILE
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fi
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fi
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if [ -f $CACHE_VALUE_FILE ]; then
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echo `cat $CACHE_VALUE_FILE` > $KVM_LAPIC_FILE
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fi
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return 0
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}
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stop() {
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[ "$1" = "full_rollback" ] && teardown_kvm_mod_low_latency
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enable_ksm
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return "$?"
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}
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verify() {
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if [ -f /sys/module/kvm/parameters/kvmclock_periodic_sync ]; then
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test "$(cat /sys/module/kvm/parameters/kvmclock_periodic_sync)" = 0
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retval=$?
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fi
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if [ $retval -eq 0 -a -f /sys/module/kvm_intel/parameters/ple_gap ]; then
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test "$(cat /sys/module/kvm_intel/parameters/ple_gap)" = 0
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retval=$?
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fi
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return $retval
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}
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process $@
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