Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
MIME-Version: 1.0
References: <1561682593-12071-1-git-send-email-wanpengli@tencent.com>
 <20190628011012.GA19488@lerouge> <CANRm+CxUpwZ9KwOcQp=Ok64giyjjcJOGb2=zU6vayQzLqYvpXQ@mail.gmail.com>
 <alpine.DEB.2.21.1910231028250.2308@nanos.tec.linutronix.de>
In-Reply-To: <alpine.DEB.2.21.1910231028250.2308@nanos.tec.linutronix.de>
From:   Wanpeng Li <kernellwp@gmail.com>
Date:   Mon, 6 Jan 2020 14:21:13 +0800
Message-ID: <CANRm+Cw1eTNgB1r79J7U__ynio7pMSR4Xa35XuQuj-JKAQGxmg@mail.gmail.com>
Subject: Re: [PATCH v2] sched/nohz: Optimize get_nohz_timer_target()
To:     Thomas Gleixner <tglx@linutronix.de>
Cc:     LKML <linux-kernel@vger.kernel.org>,
        Ingo Molnar <mingo@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>, kvm <kvm@vger.kernel.org>,
        Frederic Weisbecker <frederic@kernel.org>
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Hi Thomas,
On Wed, 23 Oct 2019 at 16:29, Thomas Gleixner <tglx@linutronix.de> wrote:
>
> On Wed, 23 Oct 2019, Wanpeng Li wrote:
> > I didn't see your refactor to get_nohz_timer_target() which you
> > mentioned in IRC after four months, I can observe cyclictest drop from
> > 4~5us to 8us in kvm guest(we offload the lapic timer emulation to
> > housekeeping cpu to avoid timer fire external interrupt on the pCPU
> > which vCPU resident incur a vCPU vmexit) w/o this patch in the case of
> > there is no busy housekeeping cpu. The score can be recovered after I
> > give stress to create a busy housekeeping cpu.
> >
> > Could you consider applying this patch for temporary since I'm not
> > sure when the refactor can be ready.
>
> Yeah. It's delayed (again).... Will pick that up.

I didn't find WIP tag for this work after ~half year since v4 was
posted https://lkml.org/lkml/2019/6/28/231 Could you apply this patch
for temporary because the completion time of refactor is not
deterministic.

    Wanpeng