From: Wanpeng Li <kernellwp@gmail.com>
To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc: Paolo Bonzini <pbonzini@redhat.com>,
Sean Christopherson <sean.j.christopherson@intel.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
Haiwei Li <lihaiwei@tencent.com>
Subject: [PATCH v3 0/5] KVM: VMX: Tscdeadline timer emulation fastpath
Date: Fri, 24 Apr 2020 14:22:39 +0800 [thread overview]
Message-ID: <1587709364-19090-1-git-send-email-wanpengli@tencent.com> (raw)
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: 2885 -> 2431.25 15.7%
tscdeadline: 5668.75 -> 5188.5 8.4%
w/ adaptive advance timer default -1:
tscdeadline_immed: 2965.25 -> 2520 15.0%
tscdeadline: 4663.75 -> 4537 2.7%
Tested-by: Haiwei Li <lihaiwei@tencent.com>
Cc: Haiwei Li <lihaiwei@tencent.com>
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 (5):
KVM: VMX: Introduce generic fastpath handler
KVM: X86: Introduce need_cancel_enter_guest 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 | 1 +
arch/x86/kvm/lapic.c | 18 +++++++++-----
arch/x86/kvm/vmx/vmx.c | 52 ++++++++++++++++++++++++++++++++++-------
arch/x86/kvm/x86.c | 40 ++++++++++++++++++++++++-------
arch/x86/kvm/x86.h | 1 +
virt/kvm/kvm_main.c | 1 +
6 files changed, 91 insertions(+), 22 deletions(-)
--
2.7.4
next reply other threads:[~2020-04-24 6:22 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-24 6:22 Wanpeng Li [this message]
2020-04-24 6:22 ` [PATCH v3 1/5] KVM: VMX: Introduce generic fastpath handler Wanpeng Li
2020-04-27 18:26 ` Sean Christopherson
2020-04-28 0:47 ` Wanpeng Li
2020-04-24 6:22 ` [PATCH v3 2/5] KVM: X86: Introduce need_cancel_enter_guest helper Wanpeng Li
2020-04-26 2:05 ` Wanpeng Li
2020-04-27 18:36 ` Sean Christopherson
2020-04-28 0:44 ` Wanpeng Li
2020-04-28 1:03 ` Sean Christopherson
2020-04-27 18:30 ` Sean Christopherson
2020-04-28 7:17 ` Wanpeng Li
2020-04-24 6:22 ` [PATCH v3 3/5] KVM: VMX: Optimize posted-interrupt delivery for timer fastpath Wanpeng Li
2020-04-27 18:37 ` Sean Christopherson
2020-04-24 6:22 ` [PATCH v3 4/5] KVM: X86: TSCDEADLINE MSR emulation fastpath Wanpeng Li
2020-04-27 18:38 ` Sean Christopherson
2020-04-24 6:22 ` [PATCH v3 5/5] KVM: VMX: Handle preemption timer fastpath Wanpeng Li
2020-04-27 18:42 ` Sean Christopherson
2020-04-28 0:45 ` Wanpeng Li
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