On 28/04/20 08:23, Wanpeng Li wrote: > IPI and Timer cause the main vmexits in cloud environment observation, > after single target IPI fastpath, let's optimize tscdeadline timer > latency by introducing tscdeadline timer emulation fastpath, it will > skip various KVM related checks when possible. i.e. after vmexit due > to tscdeadline timer emulation, handle it and vmentry immediately > without checking various kvm stuff when possible. > > Testing on SKX Server. > > cyclictest in guest(w/o mwait exposed, adaptive advance lapic timer is default -1): > > 5540.5ns -> 4602ns 17% > > kvm-unit-test/vmexit.flat: > > w/o avanced timer: > tscdeadline_immed: 3028.5 -> 2494.75 17.6% > tscdeadline: 5765.7 -> 5285 8.3% > > w/ adaptive advance timer default -1: > tscdeadline_immed: 3123.75 -> 2583 17.3% > tscdeadline: 4663.75 -> 4537 2.7% > > Tested-by: Haiwei Li <lihaiwei@xxxxxxxxxxx> > Cc: Haiwei Li <lihaiwei@xxxxxxxxxxx> > > v3 -> v4: > * fix bad indentation > * rename CONT_RUN to REENTER_GUEST > * rename kvm_need_cancel_enter_guest to kvm_vcpu_exit_request > * rename EXIT_FASTPATH_CONT_RUN to EXIT_FASTPATH_REENTER_GUEST > * introduce EXIT_FASTPATH_NOP > * don't squish several stuffs to one patch > * REENTER_GUEST be introduced with its first usage > * introduce __handle_preemption_timer subfunction > > v2 -> v3: > * skip interrupt notify and use vmx_sync_pir_to_irr before each cont_run > * add from_timer_fn argument to apic_timer_expired > * remove all kinds of duplicate codes > > v1 -> v2: > * move more stuff from vmx.c to lapic.c > * remove redundant checking > * check more conditions to bail out CONT_RUN > * not break AMD > * not handle LVTT sepecial > * cleanup codes > > Wanpeng Li (7): > KVM: VMX: Introduce generic fastpath handler > KVM: X86: Enable fastpath when APICv is enabled > KVM: X86: Introduce more exit_fastpath_completion enum values > KVM: X86: Introduce kvm_vcpu_exit_request() helper > KVM: VMX: Optimize posted-interrupt delivery for timer fastpath > KVM: X86: TSCDEADLINE MSR emulation fastpath > KVM: VMX: Handle preemption timer fastpath > > arch/x86/include/asm/kvm_host.h | 3 ++ > arch/x86/kvm/lapic.c | 18 +++++++---- > arch/x86/kvm/svm/svm.c | 11 ++++--- > arch/x86/kvm/vmx/vmx.c | 66 +++++++++++++++++++++++++++++++++-------- > arch/x86/kvm/x86.c | 44 ++++++++++++++++++++------- > arch/x86/kvm/x86.h | 3 +- > virt/kvm/kvm_main.c | 1 + > 7 files changed, 110 insertions(+), 36 deletions(-) > Queued all except 2, pending testing (and understanding the rationale behind patch 2). I will post separately my version of patch 3. Thanks, Paolo
