linux-kernel - Re: [PATCH 3/4] sched: introduce synchronized idle injection

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Message-ID: <20151118065233.1a883987@yairi>
Date:	Wed, 18 Nov 2015 06:52:33 -0800
From:	Jacob Pan <jacob.jun.pan@...ux.intel.com>
To:	Morten Rasmussen <morten.rasmussen@....com>
Cc:	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...nel.org>, Ingo Molnar <mingo@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	John Stultz <john.stultz@...aro.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Arjan van de Ven <arjan@...ux.intel.com>,
	Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
	Len Brown <len.brown@...el.com>,
	Rafael Wysocki <rafael.j.wysocki@...el.com>,
	Eduardo Valentin <edubezval@...il.com>,
	Paul Turner <pjt@...gle.com>, jacob.jun.pan@...ux.intel.com
Subject: Re: [PATCH 3/4] sched: introduce synchronized idle injection

On Wed, 18 Nov 2015 14:04:41 +0000
Morten Rasmussen <morten.rasmussen@....com> wrote:

> Then I'm confused :-/
> 
> I see the hrtimers, but the actual idle duration appears to be in
> ticks rather than ms and then converted later.
> 
> +/* Duration of idle time in ticks of each injection period
> */ +unsigned int sysctl_sched_cfs_idle_inject_duration = 5UL;
> 
> ...and futher down we have:
> 
> +       duration_msec =
> jiffies_to_msecs(sysctl_sched_cfs_idle_inject_duration);
I used hrtimers but still round around tick boundaries of ktime.
It is more reliable than jiffies in terms of getting timely updates.

Jacob
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