The main motivation for this patch is to improve the performance of VM. This patch series introduces how to enable the timer passthrough in non-root mode. The main idea is to offload the host timer to the preemtion timer in non-root mode. Through doing this, guest can write tscdeadline msr directly in non-root mode and host timer isn't lost. If CPU is in root mode, guest timer is switched to software timer. Testing on Intel(R) Xeon(R) Platinum 8260 server. The guest OS is Debian(kernel: 4.19.28). The specific configuration is is as follows: 8 cpu, 16GB memory, guest idle=poll memcached in guest(memcached -d -t 8 -u root) I use the memtier_benchmark tool to test performance (memtier_benchmark -P memcache_text -s guest_ip -c 16 -t 32 --key-maximum=10000000000 --random-data --data-size-range=64-128 -p 11211 --generate-keys --ratio 5:1 --test-time=500) Total Ops can be improved 25% and Avg.Latency can be improved 20% when the timer-passthrough is enabled. ============================================================= | Enable timer-passth | Disable timer-passth | ============================================================= Totals Ops/sec | 514869.67 | 411766.67 | ------------------------------------------------------------- Avg.Latency | 0.99483 | 1.24294 | ============================================================= Zhimin Feng (9): KVM: vmx: hook set_next_event for getting the host tscd KVM: vmx: enable host lapic timer offload preemtion timer KVM: vmx: enable passthrough timer to guest KVM: vmx: enable passth timer switch to sw timer KVM: vmx: use tsc_adjust to enable tsc_offset timer passthrough KVM: vmx: check enable_timer_passth strictly KVM: vmx: save the initial value of host tscd KVM: vmx: Dynamically open or close the timer-passthrough for pre-vm KVM: vmx: query the state of timer-passth for vm arch/x86/include/asm/kvm_host.h | 27 ++++ arch/x86/kvm/lapic.c | 1 + arch/x86/kvm/vmx/vmx.c | 331 +++++++++++++++++++++++++++++++++++++++- arch/x86/kvm/x86.c | 26 +++- include/linux/kvm_host.h | 1 + include/uapi/linux/kvm.h | 3 + kernel/time/tick-common.c | 1 + tools/include/uapi/linux/kvm.h | 3 + virt/kvm/kvm_main.c | 1 + 9 files changed, 389 insertions(+), 5 deletions(-) -- 2.11.0