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From: Thomas Gleixner <tglx@linutronix.de>
To: Sudeep Holla <sudeep.holla@arm.com>
Cc: Kevin Hilman <khilman@baylibre.com>,
	lkml <linux-kernel@vger.kernel.org>,
	fweisbec@gmail.com, Arnd Bergmann <arnd@arndb.de>,
	Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Subject: Re: [PATCH] tick: prefer a lower rating device only if it's CPU local device
Date: Tue, 3 Jul 2018 18:08:19 +0200 (CEST)	[thread overview]
Message-ID: <alpine.DEB.2.21.1807031805560.1601@nanos.tec.linutronix.de> (raw)
In-Reply-To: <20180703154459.GA15335@e107155-lin>

On Tue, 3 Jul 2018, Sudeep Holla wrote:
> On Tue, Jul 03, 2018 at 08:04:37AM -0700, Kevin Hilman wrote:
> > / # ls -l /sys/devices/system/clocksource
> > total 0
> > drwxr-xr-x    3 root     root             0 Jan  1 00:00 clocksource0
> > drwxr-xr-x    2 root     root             0 Jan  1 00:00 power
> > -rw-r--r--    1 root     root          4096 Jan  1 00:00 uevent
> > / # cat /sys/devices/system/clocksource/clocksource0/available_clocksource
> > timer jiffies
> 
> Looks good.
> 
> > / # cat /sys/devices/system/clocksource/clocksource0/current_clocksource
> > timer
> >
> 
> OK, meson6 clocksource is active
> 
> > / # cat /sys/devices/system/clockevents/broadcast/current_device
> > meson6_tick
> 
> OK, it can support broadcast
> 
> > / # cat /sys/devices/system/clockevents/clockevent0/current_device
> > dummy_timer
> > / # cat /sys/devices/system/clockevents/clockevent1/current_device
> > dummy_timer
> > / # cat /sys/devices/system/clockevents/clockevent2/current_device
> > dummy_timer
> 
> But I can't understand why is dummy_timer the active event source and
> not meson6_tick. And you say this is working case ? Looks suspicious.

Because if it switches to broadcast mode then the meson timer cannot longer
be used as per cpu timer. It's broadcasting to all CPUs via the dummy timer.

Thanks,

	tglx

  reply	other threads:[~2018-07-03 16:08 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-09 16:02 Sudeep Holla
2018-05-13 13:09 ` [tip:timers/core] tick: Prefer " tip-bot for Sudeep Holla
2018-07-02 23:44 ` [PATCH] tick: prefer " Kevin Hilman
2018-07-03 10:53   ` Sudeep Holla
2018-07-03 15:04     ` Kevin Hilman
2018-07-03 15:44       ` Sudeep Holla
2018-07-03 16:08         ` Thomas Gleixner [this message]
2018-07-03 16:48           ` Sudeep Holla
2018-07-08 20:59             ` Martin Blumenstingl
2018-07-09 15:12               ` Sudeep Holla

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