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Groups > linux.kernel > #1501128
| From | Paolo Bonzini <pbonzini@redhat.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [PATCH 0/5] KVM: x86: cleanup and minimal speedup for APICv |
| Date | 2016-10-14 20:30 +0200 |
| Message-ID | <ssfoZ-4T2-9@gated-at.bofh.it> (permalink) |
| Organization | linux.* mail to news gateway |
On some benchmarks (e.g. netperf with ioeventfd disabled), APICv posted interrupts turn out to be slower than interrupt injection via KVM_REQ_EVENT. These patches save 40 cycles on kvm-unit-tests "inl" tests (1-2%), but I suspect the effect is bigger on workloads that inject interrupts heavily. Patches 1-2 are micro-optimization of the APICv vmentry code. The interesting one is patch 3. The aim is for APICv to not use KVM_REQ_EVENT at all for interrupts, therefore turning APICv's weakness (having to look at PIR on every vmentry) into a strength (because checking PIR.ON is cheaper than processing KVM_REQ_EVENT). I find that the new code overall makes more sense than the old one, and I like that more of the logic is contained within vmx_deliver_posted_interrupt and vmx_sync_pir_to_irr. KVM_REQ_EVENT did protect from mistakes, so the new code is more delicate, but I still prefer that to duct tape. :) Patches 4 and 5 are other cleanups. Paolo Paolo Bonzini (5): KVM: x86: avoid atomic operations on APICv vmentry KVM: x86: do not scan IRR twice on APICv vmentry KVM: x86: do not use KVM_REQ_EVENT for APICv interrupt injection KVM: x86: remove unnecessary sync_pir_to_irr KVM: vmx: clear pending interrupts on KVM_SET_LAPIC arch/x86/kvm/lapic.c | 45 +++++++++++++++++++++++++++++---------------- arch/x86/kvm/lapic.h | 4 ++-- arch/x86/kvm/vmx.c | 44 ++++++++++++++++++++++++++++++++------------ arch/x86/kvm/x86.c | 45 +++++++++++++++++++++++++-------------------- 4 files changed, 88 insertions(+), 50 deletions(-) -- 1.8.3.1
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[PATCH 0/5] KVM: x86: cleanup and minimal speedup for APICv Paolo Bonzini <pbonzini@redhat.com> - 2016-10-14 20:30 +0200
[PATCH 3/5] KVM: x86: do not use KVM_REQ_EVENT for APICv interrupt injection Paolo Bonzini <pbonzini@redhat.com> - 2016-10-14 20:30 +0200
Re: [PATCH 3/5] KVM: x86: do not use KVM_REQ_EVENT for APICv interrupt injection Radim Krčmář <rkrcmar@redhat.com> - 2016-10-26 22:10 +0200
[PATCH 2/5] KVM: x86: do not scan IRR twice on APICv vmentry Paolo Bonzini <pbonzini@redhat.com> - 2016-10-14 20:30 +0200
Re: [PATCH 2/5] KVM: x86: do not scan IRR twice on APICv vmentry Wanpeng Li <kernellwp@gmail.com> - 2016-10-18 08:10 +0200
Re: [PATCH 2/5] KVM: x86: do not scan IRR twice on APICv vmentry Radim Krčmář <rkrcmar@redhat.com> - 2016-10-26 22:00 +0200
[PATCH 1/5] KVM: x86: avoid atomic operations on APICv vmentry Paolo Bonzini <pbonzini@redhat.com> - 2016-10-14 20:30 +0200
Re: [PATCH 1/5] KVM: x86: avoid atomic operations on APICv vmentry Paolo Bonzini <pbonzini@redhat.com> - 2016-10-14 21:00 +0200
Re: [PATCH 1/5] KVM: x86: avoid atomic operations on APICv vmentry Nadav Amit <nadav.amit@gmail.com> - 2016-10-14 21:50 +0200
Re: [PATCH 1/5] KVM: x86: avoid atomic operations on APICv vmentry Paolo Bonzini <pbonzini@redhat.com> - 2016-10-15 09:50 +0200
Re: [PATCH 1/5] KVM: x86: avoid atomic operations on APICv vmentry "Michael S. Tsirkin" <mst@redhat.com> - 2016-10-16 04:40 +0200
Re: [PATCH 1/5] KVM: x86: avoid atomic operations on APICv vmentry "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-10-19 20:00 +0200
Re: [PATCH 1/5] KVM: x86: avoid atomic operations on APICv vmentry "Michael S. Tsirkin" <mst@redhat.com> - 2016-10-27 00:00 +0200
Re: [PATCH 1/5] KVM: x86: avoid atomic operations on APICv vmentry Nadav Amit <nadav.amit@gmail.com> - 2016-10-14 21:00 +0200
Re: [PATCH 1/5] KVM: x86: avoid atomic operations on APICv vmentry "Michael S. Tsirkin" <mst@redhat.com> - 2016-10-16 05:30 +0200
Re: [PATCH 1/5] KVM: x86: avoid atomic operations on APICv vmentry Paolo Bonzini <pbonzini@redhat.com> - 2016-10-17 13:10 +0200
Re: [PATCH 1/5] KVM: x86: avoid atomic operations on APICv vmentry Radim Krčmář <rkrcmar@redhat.com> - 2016-10-26 22:00 +0200
Re: [PATCH 1/5] KVM: x86: avoid atomic operations on APICv vmentry "Michael S. Tsirkin" <mst@redhat.com> - 2016-10-26 23:50 +0200
[PATCH 5/5] KVM: vmx: clear pending interrupts on KVM_SET_LAPIC Paolo Bonzini <pbonzini@redhat.com> - 2016-10-14 20:30 +0200
Re: [PATCH 5/5] KVM: vmx: clear pending interrupts on KVM_SET_LAPIC Radim Krčmář <rkrcmar@redhat.com> - 2016-10-26 22:10 +0200
Re: [PATCH 0/5] KVM: x86: cleanup and minimal speedup for APICv "Michael S. Tsirkin" <mst@redhat.com> - 2016-10-27 00:00 +0200
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