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From: Peter Zijlstra <peterz@infradead.org>
To: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: anna-maria@linutronix.de, tglx@linutronix.de,
	frederic@kernel.org, gautham.shenoy@amd.com,
	linux-kernel@vger.kernel.org, daniel.lezcano@linaro.org,
	linux-pm@vger.kernel.org, mingo@redhat.com,
	juri.lelli@redhat.com, vincent.guittot@linaro.org,
	dietmar.eggemann@arm.com, rostedt@goodmis.org,
	bsegall@google.com, mgorman@suse.de, bristot@redhat.com,
	vschneid@redhat.com
Subject: Re: [RFC][PATCH 1/3] cpuidle: Inject tick boundary state
Date: Mon, 31 Jul 2023 20:06:01 +0200	[thread overview]
Message-ID: <20230731180601.GS29590@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <CAJZ5v0jz1aZdNHPH5x=VoDjfdMnD_+iE2CuYN5=nk=CMxSkXpA@mail.gmail.com>

On Mon, Jul 31, 2023 at 07:27:27PM +0200, Rafael J. Wysocki wrote:

> BTW, note that teo records timers as "hits", because it has an idea
> about when the next timer should occur and that's because it calls
> tick_nohz_get_sleep_length().
> 
> If it doesn't call that function, it will not be able to tell the
> difference between a non-tick timer and any other wakeup, so the
> non-tick timer wakeups will then be recorded as "intercepts" which
> will skew it towards shallow states over time.  That's one of the
> reasons why I would prefer to only avoid calling
> tick_nohz_get_sleep_length() when the candidate idle state is really
> shallow.

Can be fixed using tick_nohz_get_next_hrtimer() I think. Let me try that
tomorrow.

  reply	other threads:[~2023-07-31 18:06 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-07-28 14:55 [RFC][PATCH 0/3] cpuidle,teo: Improve TEO tick decisions Peter Zijlstra
2023-07-28 14:55 ` [RFC][PATCH 1/3] cpuidle: Inject tick boundary state Peter Zijlstra
2023-07-28 15:36   ` Rafael J. Wysocki
2023-07-29  8:44     ` Peter Zijlstra
2023-07-31  8:01       ` Rafael J. Wysocki
2023-07-31  9:09         ` Peter Zijlstra
2023-07-31 10:35           ` Rafael J. Wysocki
2023-07-31 11:00             ` Rafael J. Wysocki
2023-07-31 11:38             ` Peter Zijlstra
2023-07-31 16:55               ` Rafael J. Wysocki
2023-07-31 17:27                 ` Rafael J. Wysocki
2023-07-31 18:06                   ` Peter Zijlstra [this message]
2023-08-02 10:34                 ` Peter Zijlstra
2023-08-02 12:44                   ` Rafael J. Wysocki
2023-08-02 13:23                     ` Peter Zijlstra
2023-07-28 14:55 ` [RFC][PATCH 2/3] cpuidle,teo: Improve NOHZ management Peter Zijlstra
2023-07-28 16:56   ` Rafael J. Wysocki
2023-07-28 22:01     ` Peter Zijlstra
2023-07-31 10:17       ` Rafael J. Wysocki
2023-07-31 12:02         ` Peter Zijlstra
2023-07-31 17:20           ` Rafael J. Wysocki
2023-07-28 14:55 ` [RFC][PATCH 3/3] cpuidle,teo: Improve state selection Peter Zijlstra
2023-07-28 17:07   ` Rafael J. Wysocki
2023-07-29  8:46     ` Peter Zijlstra
2023-07-31 11:46 ` [RFC][PATCH 0/3] cpuidle,teo: Improve TEO tick decisions Anna-Maria Behnsen
2023-07-31 17:51   ` Rafael J. Wysocki
2023-08-02  8:12     ` Anna-Maria Behnsen

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