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From: marc.zyngier@arm.com (Marc Zyngier)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2 00/15] Make SMP timers standalone
Date: Thu, 05 Jan 2012 10:33:32 +0000	[thread overview]
Message-ID: <4F057C7C.6050509@arm.com> (raw)
In-Reply-To: <20120104214748.GH11810@n2100.arm.linux.org.uk>

On 04/01/12 21:47, Russell King - ARM Linux wrote:
> On Wed, Jan 04, 2012 at 05:39:16PM +0000, Marc Zyngier wrote:
>> On 22/12/11 19:32, Russell King - ARM Linux wrote:
>>> You're also aware I assume that local timers are different from the global
>>> timer itself, and require to have additional callbacks for broadcasting
>>> the global timer tick?
>>
>> I was under the impression that we either have the global timer together
>> with broadcasting or the local timers. Completely removing the broadcast
>> callback doesn't seem to generate any ill effect as long as the local
>> timers are used instead of the global timer (which of course requires
>> broadcast in the SMP configuration).
> 
> I believe even if you have local timers, there are situations where the
> these will be disabled and the kernel will switch to broadcasting from a
> global timer tick.  I think such a scenario would be like that encountered
> with OMAP, where suspending a CPU stops its TWD - meaning that the TWD
> can't be used to wake the CPU from one of the deeper idle states.

Yes, being able to wake up is definitely a good reason to keep a global
timer around, not to mention other artifacts (TWD calibration being one,
though on its way out thanks to LinusW patch series).

	M.
-- 
Jazz is not dead. It just smells funny...

  parent reply	other threads:[~2012-01-05 10:33 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-12-22 17:27 [PATCH v2 00/15] Make SMP timers standalone Marc Zyngier
2011-12-22 17:27 ` [PATCH v2 01/15] ARM: local timers: allow smp_twd to be used standalone Marc Zyngier
2011-12-22 20:38   ` Russell King - ARM Linux
2011-12-22 17:27 ` [PATCH v2 02/15] ARM: smp_twd: add device tree support Marc Zyngier
2011-12-22 17:27 ` [PATCH v2 03/15] ARM: local timers: switch realview to standalone smp_twd Marc Zyngier
2011-12-22 17:27 ` [PATCH v2 04/15] ARM: local timers: switch vexpress " Marc Zyngier
2011-12-22 17:27 ` [PATCH v2 05/15] ARM: local timers: remove localtimer.c from plat-versatile Marc Zyngier
2011-12-22 17:27 ` [PATCH v2 06/15] ARM: local timers: switch tegra to standalone smp_twd Marc Zyngier
2011-12-22 19:22   ` Colin Cross
2011-12-22 17:27 ` [PATCH v2 07/15] ARM: local timers: switch omap4 " Marc Zyngier
2011-12-23  6:37   ` Shilimkar, Santosh
2011-12-22 17:27 ` [PATCH v2 08/15] ARM: local timers: switch shmobile " Marc Zyngier
2011-12-22 17:27 ` [PATCH v2 09/15] ARM: local timers: switch ux500 " Marc Zyngier
2011-12-22 17:27 ` [PATCH v2 10/15] ARM: local timers: switch highbank " Marc Zyngier
2011-12-22 17:27 ` [PATCH v2 11/15] ARM: local timers: switch imx6q " Marc Zyngier
2011-12-25 13:40   ` Shawn Guo
2011-12-22 17:27 ` [PATCH v2 12/15] ARM: smp_twd: remove support for non-standalone version Marc Zyngier
2011-12-22 17:27 ` [PATCH v2 13/15] ARM: local timers: make MCT timer standalone Marc Zyngier
2011-12-22 17:27 ` [PATCH v2 14/15] ARM: local timers: make MSM timers standalone Marc Zyngier
2011-12-22 17:27 ` [PATCH v2 15/15] ARM: local timers: Remove CONFIG_LOCAL_TIMERS support Marc Zyngier
2011-12-22 19:32 ` [PATCH v2 00/15] Make SMP timers standalone Russell King - ARM Linux
2012-01-04 17:39   ` Marc Zyngier
2012-01-04 21:47     ` Russell King - ARM Linux
2012-01-05  0:00       ` Linus Walleij
2012-01-05 11:08         ` Marc Zyngier
2012-01-05 11:13           ` Shilimkar, Santosh
2012-01-05 11:19             ` Marc Zyngier
2012-01-05 11:26               ` Russell King - ARM Linux
2012-01-05 11:35                 ` Marc Zyngier
2012-01-05 12:10                   ` Russell King - ARM Linux
2012-01-05 16:13                     ` Marc Zyngier
2012-01-05 16:26                       ` Russell King - ARM Linux
2012-01-05 16:55                         ` Russell King - ARM Linux
2012-01-05 11:31               ` Shilimkar, Santosh
2012-01-05 10:33       ` Marc Zyngier [this message]
2012-01-05 10:45         ` Shilimkar, Santosh
2012-01-05  1:17     ` David Brown
2012-01-05 10:26       ` Linus Walleij
2012-01-05 11:01         ` Russell King - ARM Linux
2012-01-05 19:34         ` johlstei

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