linux-kernel - 答复: [PATCH] KVM: Consider SMT idle status when halt polling

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Message-ID: <1c26ad3589f8495f9f30fdab485d353d@baidu.com>
Date:   Thu, 22 Jul 2021 07:10:55 +0000
From:   "Li,Rongqing" <lirongqing@...du.com>
To:     Wanpeng Li <kernellwp@...il.com>
CC:     Paolo Bonzini <pbonzini@...hat.com>,
        Ingo Molnar <mingo@...hat.com>,
        "Peter Zijlstra" <peterz@...radead.org>, kvm <kvm@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: 答复: [PATCH] KVM: Consider SMT idle status when halt polling



> -----邮件原件-----
> 发件人: Wanpeng Li <kernellwp@...il.com>
> 发送时间: 2021年7月22日 13:55
> 收件人: Li,Rongqing <lirongqing@...du.com>
> 抄送: Paolo Bonzini <pbonzini@...hat.com>; Ingo Molnar
> <mingo@...hat.com>; Peter Zijlstra <peterz@...radead.org>; kvm
> <kvm@...r.kernel.org>; LKML <linux-kernel@...r.kernel.org>
> 主题: Re: [PATCH] KVM: Consider SMT idle status when halt polling
> 
> On Thu, 22 Jul 2021 at 12:07, Li RongQing <lirongqing@...du.com> wrote:
> >
> > SMT siblings share caches and other hardware, halt polling will
> > degrade its sibling performance if its sibling is busy
> 
> Do you have any real scenario benefits? As the polling nature, some cloud
> providers will configure to their preferred balance of cpu usage and
> performance, and other cloud providers for their NFV scenarios which are more
> sensitive to latency are vCPU and pCPU 1:1 pin，you
> destroy these setups.
>
>     Wanpeng

True, it benefits for our real scenario.

this patch can lower our workload compute latency in our multiple cores VM which vCPU and pCPU is 1:1 pin, and the workload with lots of computation and networking packets.

-Li