| Message ID | 1588055009-12677-1-git-send-email-wanpengli@tencent.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | KVM: VMX: Tscdeadline timer emulation fastpath | expand |
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@tencent.com> > Cc: Haiwei Li <lihaiwei@tencent.com> > > 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
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@tencent.com> Cc: Haiwei Li <lihaiwei@tencent.com> 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(-)