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From: Peter Zijlstra <peterz@infradead.org>
To: Yang Zhang <yang.zhang.wz@gmail.com>
Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
	wanpeng.li@hotmail.com, mst@redhat.com, pbonzini@redhat.com,
	tglx@linutronix.de, rkrcmar@redhat.com, dmatlack@google.com,
	agraf@suse.de, linux-doc@vger.kernel.org,
	Quan Xu <quan.xu0@gmail.com>, Ingo Molnar <mingo@redhat.com>
Subject: Re: [RFC PATCH v2 7/7] sched/idle: update poll time when wakeup from idle
Date: Tue, 29 Aug 2017 14:46:55 +0200	[thread overview]
Message-ID: <20170829124655.ann5cipoubl5lppn@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <1504007201-12904-8-git-send-email-yang.zhang.wz@gmail.com>

On Tue, Aug 29, 2017 at 11:46:41AM +0000, Yang Zhang wrote:
> In ttwu_do_wakeup, it will update avg_idle when wakeup from idle. Here
> we just reuse this logic to update the poll time. It may be a little
> late to update the poll in ttwu_do_wakeup, but the test result shows no
> obvious performance gap compare with updating poll in irq handler.
> 
> one problem is that idle_stamp only used when using CFS scheduler. But
> it is ok since it is the default policy for scheduler and only consider
> it should enough.
> 
> Signed-off-by: Yang Zhang <yang.zhang.wz@gmail.com>
> Signed-off-by: Quan Xu <quan.xu0@gmail.com>

Same broken SoB chain, and not a useful word on why you need to adjust
this crap to begin with. What you want that poll duration to be related
to is the cost of a VMEXIT/VMENTER cycle, not however long we happened
to be idle.

So no.

  reply	other threads:[~2017-08-29 12:47 UTC|newest]

Thread overview: 47+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-08-29 11:46 [RFC PATCH v2 0/7] x86/idle: add halt poll support Yang Zhang
2017-08-29 11:46 ` [RFC PATCH v2 1/7] x86/paravirt: Add pv_idle_ops to paravirt ops Yang Zhang
2017-08-29 11:46   ` Yang Zhang
2017-08-29 13:55   ` Konrad Rzeszutek Wilk
2017-08-29 13:55     ` Konrad Rzeszutek Wilk
2017-08-30  7:33     ` Juergen Gross
2017-08-30  7:33     ` Juergen Gross
2017-09-01  6:50     ` Yang Zhang
2017-09-01  6:50     ` Yang Zhang
2017-08-29 11:46 ` [RFC PATCH v2 2/7] KVM guest: register kvm_idle_poll for pv_idle_ops Yang Zhang
2017-08-29 11:46 ` [RFC PATCH v2 3/7] sched/idle: Add poll before enter real idle path Yang Zhang
2017-08-29 12:45   ` Peter Zijlstra
2017-09-01  5:57     ` Quan Xu
2017-09-14  8:41       ` Quan Xu
2017-09-14  9:18         ` Borislav Petkov
2017-08-29 14:39   ` Borislav Petkov
2017-09-01  6:49     ` Quan Xu
2017-09-29 10:39       ` Quan Xu
2017-08-29 11:46 ` [RFC PATCH v2 4/7] x86/paravirt: Add update in x86/paravirt pv_idle_ops Yang Zhang
2017-08-29 11:46 ` Yang Zhang
2017-08-29 11:46 ` [RFC PATCH v2 5/7] Documentation: Add three sysctls for smart idle poll Yang Zhang
2017-08-29 11:46 ` Yang Zhang
2017-08-29 11:46   ` Yang Zhang
2017-08-29 17:20   ` Luis R. Rodriguez
2017-08-29 17:20   ` Luis R. Rodriguez
2017-08-29 17:20     ` Luis R. Rodriguez
2017-08-29 11:46 ` [RFC PATCH v2 6/7] KVM guest: introduce smart idle poll algorithm Yang Zhang
2017-08-29 11:46 ` [RFC PATCH v2 7/7] sched/idle: update poll time when wakeup from idle Yang Zhang
2017-08-29 12:46   ` Peter Zijlstra [this message]
2017-09-01  7:30     ` Yang Zhang
2017-09-29 10:29     ` Quan Xu
2017-08-29 11:58 ` [RFC PATCH v2 0/7] x86/idle: add halt poll support Alexander Graf
2017-09-01  6:21   ` Yang Zhang
2017-08-29 13:03 ` Andi Kleen
2017-08-29 14:02 ` Wanpeng Li
2017-08-29 14:27   ` Konrad Rzeszutek Wilk
2017-08-29 14:36   ` Michael S. Tsirkin
2017-09-01  6:32   ` Yang Zhang
2017-09-01  6:52     ` Wanpeng Li
2017-09-01  6:44   ` Yang Zhang
2017-09-01  6:58     ` Wanpeng Li
2017-09-01  7:53       ` Yang Zhang
2017-08-29 14:56 ` Michael S. Tsirkin
2017-09-13 11:56   ` Yang Zhang
2017-09-14  8:36     ` Quan Xu
2017-09-14  9:19       ` Wanpeng Li
2017-09-14  9:40         ` Quan Xu

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