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From: Wanpeng Li <kernellwp@gmail.com>
To: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: LKML <linux-kernel@vger.kernel.org>, kvm <kvm@vger.kernel.org>,
	Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: [PATCH v3 0/3] KVM: Yield to IPI target if necessary
Date: Tue, 11 Jun 2019 18:26:43 +0800	[thread overview]
Message-ID: <CANRm+CwgE5d0hQif0Rj-=q-orxMpSZq+tKLvrkZuatmatYxjWg@mail.gmail.com> (raw)
In-Reply-To: <20190610143420.GA6594@flask>

On Mon, 10 Jun 2019 at 22:34, Radim Krčmář <rkrcmar@redhat.com> wrote:
>
> 2019-05-30 09:05+0800, Wanpeng Li:
> > The idea is from Xen, when sending a call-function IPI-many to vCPUs,
> > yield if any of the IPI target vCPUs was preempted. 17% performance
> > increasement of ebizzy benchmark can be observed in an over-subscribe
> > environment. (w/ kvm-pv-tlb disabled, testing TLB flush call-function
> > IPI-many since call-function is not easy to be trigged by userspace
> > workload).
>
> Have you checked if we could gain performance by having the yield as an
> extension to our PV IPI call?

It will extend irq disabled time in __send_ipi_mask(). In addition,
sched yield can be used to optimize other synchronization primitives
in guest I think.

Regards,
Wanpeng Li

      parent reply	other threads:[~2019-06-11 10:26 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-30  1:05 Wanpeng Li
2019-05-30  1:05 ` [PATCH v3 1/3] KVM: X86: " Wanpeng Li
2019-05-30  1:05 ` [PATCH v3 2/3] KVM: X86: Implement PV sched yield hypercall Wanpeng Li
2019-06-10 14:17   ` Radim Krčmář
2019-06-11  8:47     ` Wanpeng Li
2019-05-30  1:05 ` [PATCH v3 3/3] KVM: X86: Expose PV_SCHED_YIELD CPUID feature bit to guest Wanpeng Li
2019-06-10  5:58 ` [PATCH v3 0/3] KVM: Yield to IPI target if necessary Wanpeng Li
2019-06-10 14:34 ` Radim Krčmář
2019-06-11  1:11   ` Sean Christopherson
2019-06-11  1:45     ` Wanpeng Li
2019-06-11  1:48       ` Nadav Amit
2019-06-11 10:02         ` Wanpeng Li
2019-06-11 16:57           ` Nadav Amit
2019-06-12  1:18             ` Wanpeng Li
2019-06-12  1:37               ` Nadav Amit
2019-06-28  9:12                 ` Wanpeng Li
2019-06-28  9:18                   ` Wanpeng Li
2019-06-11 10:26   ` Wanpeng Li [this message]

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