On Wed, 18 Jan 2023 10:30:03 +0200 Zhi Wang <zhi.wang.linux@xxxxxxxxx> wrote: Hi: No sure why the test never finishes on my testing machine. Will take a look later today. My CPU: model name : Intel(R) Core(TM) i7-8700 CPU @ 3.20GHz branch kvm.git/master top commit: 310bc39546a435c83cc27a0eba878afac0d74714 ----- [inno@inno-lk-server x86_64]$ time ./disable_exits_test VM-scoped tests start Halter vCPU thread started vCPU thread running vCPU 0 Halter vCPU thread reported its first HLT executed after 1 seconds. vCPU thread running vCPU 1 Halter vCPU had 10 halt exits Guest records 10 HLTs executed, waked 9 times Halter vCPU thread started vCPU thread running vCPU 0 ^C real 19m0.923s user 37m56.512s sys 0m1.086s ----- > On Fri, 13 Jan 2023 22:01:08 +0000 > Kechen Lu <kechenl@xxxxxxxxxx> wrote: > > Hi: > > checkpatch.pl throws a lot of warning and errors when I was trying > this series. Can you fix them? > > total: 470 errors, 22 warnings, 464 lines checked > > > Summary > > =========== > > Introduce support of vCPU-scoped ioctl with KVM_CAP_X86_DISABLE_EXITS > > cap for disabling exits to enable finer-grained VM exits disabling > > on per vCPU scales instead of whole guest. This patch series enabled > > the vCPU-scoped exits control and toggling. > > > > Motivation > > ============ > > In use cases like Windows guest running heavy CPU-bound > > workloads, disabling HLT VM-exits could mitigate host sched ctx switch > > overhead. Simply HLT disabling on all vCPUs could bring > > performance benefits, but if no pCPUs reserved for host threads, could > > happened to the forced preemption as host does not know the time to do > > the schedule for other host threads want to run. With this patch, we > > could only disable part of vCPUs HLT exits for one guest, this still > > keeps performance benefits, and also shows resiliency to host stressing > > workload running at the same time. > > > > Performance and Testing > > ========================= > > In the host stressing workload experiment with Windows guest heavy > > CPU-bound workloads, it shows good resiliency and having the ~3% > > performance improvement. E.g. Passmark running in a Windows guest > > with this patch disabling HLT exits on only half of vCPUs still > > showing 2.4% higher main score v/s baseline. > > > > Tested everything on AMD machines. > > > > v4->v5 : > > - Drop the usage of KVM request, keep the VM-scoped exits disable > > as the existing design, and only allow per-vCPU settings to > > override the per-VM settings (Sean Christopherson) > > - Refactor the disable exits selftest without introducing any > > new prerequisite patch, tests per-vCPU exits disable and overrides, > > and per-VM exits disable > > > > v3->v4 (Chao Gao) : > > - Use kvm vCPU request KVM_REQ_DISABLE_EXIT to perform the arch > > VMCS updating (patch 5) > > - Fix selftests redundant arguments (patch 7) > > - Merge overlapped fix bits from patch 4 to patch 3 > > > > v2->v3 (Sean Christopherson) : > > - Reject KVM_CAP_X86_DISABLE_EXITS if userspace disable MWAIT exits > > when MWAIT is not allowed in guest (patch 3) > > - Make userspace able to re-enable previously disabled exits (patch 4) > > - Add mwait/pause/cstate exits flag toggling instead of only hlt > > exits (patch 5) > > - Add selftests for KVM_CAP_X86_DISABLE_EXITS (patch 7) > > > > v1->v2 (Sean Christopherson) : > > - Add explicit restriction for VM-scoped exits disabling to be called > > before vCPUs creation (patch 1) > > - Use vCPU ioctl instead of 64bit vCPU bitmask (patch 5), and make exits > > disable flags check purely for vCPU instead of VM (patch 2) > > > > Best Regards, > > Kechen > > > > Kechen Lu (3): > > KVM: x86: Move *_in_guest power management flags to vCPU scope > > KVM: x86: add vCPU scoped toggling for disabled exits > > KVM: selftests: Add tests for VM and vCPU cap > > KVM_CAP_X86_DISABLE_EXITS > > > > Sean Christopherson (3): > > KVM: x86: only allow exits disable before vCPUs created > > KVM: x86: Reject disabling of MWAIT interception when not allowed > > KVM: x86: Let userspace re-enable previously disabled exits > > > > Documentation/virt/kvm/api.rst | 8 +- > > arch/x86/include/asm/kvm-x86-ops.h | 1 + > > arch/x86/include/asm/kvm_host.h | 7 + > > arch/x86/kvm/cpuid.c | 4 +- > > arch/x86/kvm/lapic.c | 7 +- > > arch/x86/kvm/svm/nested.c | 4 +- > > arch/x86/kvm/svm/svm.c | 42 +- > > arch/x86/kvm/vmx/vmx.c | 53 +- > > arch/x86/kvm/x86.c | 69 ++- > > arch/x86/kvm/x86.h | 16 +- > > include/uapi/linux/kvm.h | 4 +- > > tools/testing/selftests/kvm/Makefile | 1 + > > .../selftests/kvm/x86_64/disable_exits_test.c | 457 ++++++++++++++++++ > > 13 files changed, 626 insertions(+), 47 deletions(-) > > create mode 100644 tools/testing/selftests/kvm/x86_64/disable_exits_test.c > > >
