From: Wanpeng Li <kernellwp@gmail.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Wanpeng Li" <wanpeng.li@hotmail.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"Radim Krčmář" <rkrcmar@redhat.com>
Subject: Re: [PATCH v3 1/2] KVM: LAPIC: Tune lapic_timer_advance_ns smoothly
Date: Mon, 16 Sep 2019 16:09:55 +0800 [thread overview]
Message-ID: <CANRm+Cy-u4AJ8kBMy44JAv-7er9YmwgY0gbq1QR=Pt4MV9JvJA@mail.gmail.com> (raw)
In-Reply-To: <82ff90b6-f518-e2a8-c4f5-ef4b294af15e@redhat.com>
On Mon, 16 Sep 2019 at 15:49, Paolo Bonzini <pbonzini@redhat.com> wrote:
>
> On 16/09/19 06:02, Wanpeng Li wrote:
> > Hi Paolo,
> >
> > Something like below? It still fluctuate when running complex guest os
> > like linux. Removing timer_advance_adjust_done will hinder introduce
> > patch v3 2/2 since there is no adjust done flag in each round
> > evaluation.
>
> That's not important, since the adjustment would be continuous.
>
> How much fluctuation can you see?
After I add a trace_printk to observe more closely, the adjustment is
continuous as expected.
>
> > I have two questions here, best-effort tune always as
> > below or periodically revaluate to get conservative value and get
> > best-effort value in each round evaluation as patch v3 2/2, which one
> > do you prefer? The former one can wast time to wait sometimes and the
> > later one can not get the best latency. In addition, can the adaptive
> > tune algorithm be using in all the scenarios contain
> > RT/over-subscribe?
>
> I prefer the former, like the patch below, mostly because of the extra
> complexity of the periodic reevaluation.
How about question two?
Wanpeng
prev parent reply other threads:[~2019-09-16 8:10 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-28 8:19 [PATCH v3 1/2] KVM: LAPIC: Tune lapic_timer_advance_ns smoothly Wanpeng Li
2019-08-28 8:19 ` [PATCH v3 2/2] KVM: LAPIC: Periodically revaluate to get conservative lapic_timer_advance_ns Wanpeng Li
2019-09-11 15:45 ` [PATCH v3 1/2] KVM: LAPIC: Tune lapic_timer_advance_ns smoothly Paolo Bonzini
[not found] ` <TY2PR02MB4160421A8C88D96C8BCB971180B00@TY2PR02MB4160.apcprd02.prod.outlook.com>
2019-09-12 12:37 ` Paolo Bonzini
2019-09-16 4:02 ` Wanpeng Li
2019-09-16 7:49 ` Paolo Bonzini
2019-09-16 8:09 ` Wanpeng Li [this message]
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