From 4790e570ce0e41bde4e1866ed6e3cba723b5f4d8 Mon Sep 17 00:00:00 2001
From: Marcelo Tosatti <mtosatti@redhat.com>
Date: Wed, 4 Jul 2018 17:30:37 -0300
Subject: [PATCH] realtime-virtual-host: pin only the vcpu thread to isolated
pCPU (v2)
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)
---
profiles/realtime-virtual-host/script.sh | 31 ++++++++++++++++--------
1 file changed, 21 insertions(+), 10 deletions(-)
diff --git a/profiles/realtime-virtual-host/script.sh b/profiles/realtime-virtual-host/script.sh
index 515d2547..32e962db 100755
--- a/profiles/realtime-virtual-host/script.sh
+++ b/profiles/realtime-virtual-host/script.sh
@@ -17,20 +17,31 @@ run_tsc_deadline_latency()
for i in `seq 1000 500 7000`; do
echo $i > $KVM_LAPIC_FILE
- chrt -f 1 taskset -c $1 $QEMU -enable-kvm -device pc-testdev \
+
+ unixpath=`mktemp`
+
+ chrt -f 1 $QEMU -S -enable-kvm -device pc-testdev \
-device isa-debug-exit,iobase=0xf4,iosize=0x4 \
-display none -serial stdio -device pci-testdev \
-kernel "$TSCDEADLINE_LATENCY" \
- -cpu host | grep latency | cut -f 2 -d ":" > $dir/out
-
- if [ ! -f $dir/out ]; then
- die running $TSCDEADLINE_LATENCY failed
- fi
+ -cpu host \
+ -mon chardev=char0,mode=readline \
+ -chardev socket,id=char0,nowait,path=$unixpath,server | grep latency | cut -f 2 -d ":" > $dir/out &
+
+ sleep 1s
+ pidofvcpu=`echo "info cpus" | nc -U $unixpath | grep thread_id | cut -f 3 -d "=" | tr -d "\r"`
+ taskset -p -c $1 $pidofvcpu >/dev/null
+ echo "cont" | nc -U $unixpath >/dev/null
+ wait
+
+ if [ ! -f $dir/out ]; then
+ die running $TSCDEADLINE_LATENCY failed
+ fi
- tmp=$(wc -l $dir/out | awk '{ print $1 }')
- if [ $tmp -eq 0 ]; then
- die running $TSCDEADLINE_LATENCY failed
- fi
+ tmp=$(wc -l $dir/out | awk '{ print $1 }')
+ if [ $tmp -eq 0 ]; then
+ die running $TSCDEADLINE_LATENCY failed
+ fi
A=0
while read l; do