Hi everyone, I'm having the following qemu issue since about February on Xubuntu.
Steps to reproduce: 1) Boot host and boot qemu guest - everything works perfect 2) Shutdown qemu guest 3) Suspend host and resume host 4) Boot qemu guest again - the guest is now extremely slow Current system setup: host: kernel 4.8.0-27-generic (also reproducible with older kernel versions) qemu guest: Linux or Windows affected (tested both) I've tried to debug the issue on my own with the following results: ------------------------------------------------------------------------------------------------------------------------------ https://www.evonide.com/images/qemu_problem.png - This shows "perf top $QEMU_PID" from guest boot to shutdown for three different scenarios: Left: normal guest behavior after fresh boot of host system Middle: very slow guest after host was suspended and resumed Right: test run with disabled HPET (since I initially assumed some problems with HPET) https://www.evonide.com/images/qemu_hpet_investigation.png - Results of "perf record -g" and "perf report" According to stefanha (qemu IRC) this doesn't seem to indicate any error sources. https://www.evonide.com/images/qemu_vm_exit_healthy_vs_unhealthy.png - Results of running: "perf record -a -e kvm:kvm_exit" and "perf report" from guest boot to shutdown - Left: normal situation (after fresh host boot) - Right: bad situation (after suspend and resume on host and boot of qemu guest) There were ~300 out of order events reported by perf for the "bad" scenario (vs. only 2 for the "good" scenario). ------------------------------------------------------------------------------------------------------------------------------ I was also recommended to check the host timers (e.g. /proc/timer_list). However, this file has more than 800 lines and I am unsure what to look for. Please let me know if you need further information on this issue. Best regards, Ruslan Habalov (Evonide)
