From: Marcelo Tosatti <mtosatti@redhat.com>
To: kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [patch 0/3] KVM KVM_HC_RT_PRIO hypercall support
Date: Thu, 21 Sep 2017 08:38:35 -0300 [thread overview]
Message-ID: <20170921113835.031375194@redhat.com> (raw)
When executing guest vcpu-0 with FIFO:1 priority, which is necessary to
deal with the following situation:
VCPU-0 (housekeeping VCPU) VCPU-1 (realtime VCPU)
raw_spin_lock(A)
interrupted, schedule task T-1 raw_spin_lock(A) (spin)
raw_spin_unlock(A)
Certain operations must interrupt guest vcpu-0 (see trace below).
To fix this issue, only change guest vcpu-0 to FIFO priority
on spinlock critical sections (see patch).
Hang trace
==========
Without FIFO priority:
qemu-kvm-6705 [002] ....1.. 767785.648964: kvm_exit: reason IO_INSTRUCTION rip 0xe8fe info 1f00039 0
qemu-kvm-6705 [002] ....1.. 767785.648965: kvm_exit: reason IO_INSTRUCTION rip 0xe911 info 3f60008 0
qemu-kvm-6705 [002] ....1.. 767785.648968: kvm_exit: reason IO_INSTRUCTION rip 0x8984 info 608000b 0
qemu-kvm-6705 [002] ....1.. 767785.648971: kvm_exit: reason IO_INSTRUCTION rip 0xb313 info 1f70008 0
qemu-kvm-6705 [002] ....1.. 767785.648974: kvm_exit: reason IO_INSTRUCTION rip 0xb514 info 3f60000 0
qemu-kvm-6705 [002] ....1.. 767785.648977: kvm_exit: reason PENDING_INTERRUPT rip 0x8052 info 0 0
qemu-kvm-6705 [002] ....1.. 767785.648980: kvm_exit: reason IO_INSTRUCTION rip 0xeee6 info 200040 0
qemu-kvm-6705 [002] ....1.. 767785.648999: kvm_exit: reason EPT_MISCONFIG rip 0x2120 info 0 0
With FIFO priority:
qemu-kvm-7636 [002] ....1.. 768218.205065: kvm_exit: reason IO_INSTRUCTION rip 0xb313 info 1f70008 0
qemu-kvm-7636 [002] ....1.. 768218.205068: kvm_exit: reason IO_INSTRUCTION rip 0x8984 info 608000b 0
qemu-kvm-7636 [002] ....1.. 768218.205071: kvm_exit: reason IO_INSTRUCTION rip 0xb313 info 1f70008 0
qemu-kvm-7636 [002] ....1.. 768218.205074: kvm_exit: reason IO_INSTRUCTION rip 0x8984 info 608000b 0
qemu-kvm-7636 [002] ....1.. 768218.205077: kvm_exit: reason IO_INSTRUCTION rip 0xb313 info 1f70008 0
..
Performance numbers (kernel compilation with make -j2)
======================================================
With hypercall: 4:40. (make -j2)
Without hypercall: 3:38. (make -j2)
Note for NFV workloads spinlock performance is not relevant
since DPDK should not enter the kernel (and housekeeping vcpu
performance is far from a key factor).
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
next reply other threads:[~2017-09-21 11:43 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-21 11:38 Marcelo Tosatti [this message]
2017-09-21 11:38 ` [patch 1/3] KVM: x86: add per-vcpu option to set guest vcpu -RT priority Marcelo Tosatti
2017-09-21 11:38 ` [patch 2/3] KVM: x86: KVM_HC_RT_PRIO hypercall (host-side) Marcelo Tosatti
2017-09-21 13:32 ` Konrad Rzeszutek Wilk
2017-09-21 13:49 ` Paolo Bonzini
2017-09-22 1:08 ` Marcelo Tosatti
2017-09-22 7:23 ` Paolo Bonzini
2017-09-22 12:24 ` Marcelo Tosatti
2017-09-21 11:38 ` [patch 3/3] x86: kvm guest side support for KVM_HC_RT_PRIO hypercall Marcelo Tosatti
2017-09-21 13:36 ` Konrad Rzeszutek Wilk
2017-09-21 14:06 ` Peter Zijlstra
2017-09-22 1:10 ` Marcelo Tosatti
2017-09-22 10:00 ` Peter Zijlstra
2017-09-22 10:56 ` Peter Zijlstra
2017-09-22 12:33 ` Marcelo Tosatti
2017-09-22 12:55 ` Peter Zijlstra
2017-09-23 10:56 ` Paolo Bonzini
2017-09-23 13:41 ` Peter Zijlstra
2017-09-24 13:05 ` Paolo Bonzini
2017-09-25 2:57 ` Marcelo Tosatti
2017-09-25 9:13 ` Peter Zijlstra
2017-09-25 15:12 ` Paolo Bonzini
2017-09-26 22:49 ` [patch 3/3] x86: kvm guest side support for KVM_HC_RT_PRIO hypercall\ Marcelo Tosatti
2017-09-27 9:37 ` Paolo Bonzini
2017-09-28 0:44 ` Marcelo Tosatti
2017-09-28 7:22 ` Paolo Bonzini
2017-09-28 21:35 ` Marcelo Tosatti
2017-09-28 21:41 ` Marcelo Tosatti
2017-09-29 8:18 ` Paolo Bonzini
2017-09-29 16:40 ` Marcelo Tosatti
2017-09-29 17:05 ` Paolo Bonzini
2017-09-29 20:17 ` Marcelo Tosatti
2017-10-02 12:30 ` Paolo Bonzini
2017-10-02 12:48 ` Peter Zijlstra
2017-09-26 23:22 ` [patch 3/3] x86: kvm guest side support for KVM_HC_RT_PRIO hypercall Marcelo Tosatti
2017-09-25 16:20 ` Konrad Rzeszutek Wilk
2017-09-22 12:16 ` Marcelo Tosatti
2017-09-22 12:31 ` Peter Zijlstra
2017-09-22 12:36 ` Marcelo Tosatti
2017-09-22 12:59 ` Peter Zijlstra
2017-09-25 1:52 ` Marcelo Tosatti
2017-09-25 8:35 ` Peter Zijlstra
2017-09-22 12:40 ` [patch 3/3] x86: kvm guest side support for KVM_HC_RT_PRIO hypercall\ Marcelo Tosatti
2017-09-22 13:01 ` Peter Zijlstra
2017-09-25 2:22 ` Marcelo Tosatti
2017-09-25 8:58 ` Peter Zijlstra
2017-09-25 10:41 ` Thomas Gleixner
2017-09-25 18:28 ` Jan Kiszka
2017-09-21 17:45 ` [patch 0/3] KVM KVM_HC_RT_PRIO hypercall support Jan Kiszka
2017-09-22 1:19 ` Marcelo Tosatti
2017-09-22 6:23 ` Jan Kiszka
2017-09-26 23:59 ` Marcelo Tosatti
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