From: Kumar Gala <galak@kernel.crashing.org>
To: Zhao Chenhui <chenhui.zhao@freescale.com>
Cc: "linuxppc-dev@lists.ozlabs.org list"
<linuxppc-dev@lists.ozlabs.org>,
Scott Wood <scottwood@freescale.com>,
"linux-kernel@vger.kernel.org list"
<linux-kernel@vger.kernel.org>, Li Yang <leoli@freescale.com>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>
Subject: Re: [PATCH v6 1/5] powerpc/85xx: implement hardware timebase sync
Date: Thu, 28 Jun 2012 13:30:26 -0500 [thread overview]
Message-ID: <D2BA086B-6EB3-4853-B901-FA37DCCDC134@kernel.crashing.org> (raw)
In-Reply-To: <1340880651.20977.83.camel@pasglop>
On Jun 28, 2012, at 5:50 AM, Benjamin Herrenschmidt wrote:
> On Thu, 2012-06-28 at 11:38 +0800, Zhao Chenhui wrote:
>>
>>
>> The bootloader have done a timebase sync. If we do not need KEXEC or
>> HOTPLUG_CPU feature, it is unnecessary to do it again at boot time of
>> kernel. I only compile the timebase sync routines
>> when users enable KEXEC or HOTPLUG_CPU.
>
> Still, how much are you really saving ? Is it worth the added mess and
> loss of test coverage ?
>
> We have too many conditional stuff like that already.
>
> Cheers,
> Ben.
>
I'd also be interested to know how long it actually takes to do time base sync this way. Since you are freezing the timers for some period how long does it really take between the freeze/unfreeze in mpc85xx_give_timebase()
+ mpc85xx_timebase_freeze(1);
...
+ mpc85xx_timebase_freeze(0);
You can use ATBL/U as a way to see # of cycles taken.
- k
next prev parent reply other threads:[~2012-06-28 18:30 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-26 10:25 Zhao Chenhui
2012-06-26 10:25 ` [PATCH v6 2/5] powerpc/85xx: add HOTPLUG_CPU support Zhao Chenhui
2012-06-26 10:25 ` [PATCH v6 3/5] powerpc/85xx: add sleep and deep sleep support Zhao Chenhui
2012-07-13 12:27 ` Kumar Gala
2012-06-26 10:25 ` [PATCH v6 4/5] fsl_pmc: Add API to enable device as wakeup event source Zhao Chenhui
2012-06-26 10:25 ` [PATCH v6 5/5] powerpc/85xx: add support to JOG feature using cpufreq interface Zhao Chenhui
2012-06-26 14:03 ` [PATCH v6 1/5] powerpc/85xx: implement hardware timebase sync Kumar Gala
2012-06-26 21:45 ` Scott Wood
2012-06-26 22:10 ` Benjamin Herrenschmidt
2012-06-27 10:10 ` Zhao Chenhui
2012-06-26 22:10 ` Benjamin Herrenschmidt
2012-06-27 10:21 ` Zhao Chenhui
2012-06-27 11:48 ` Benjamin Herrenschmidt
2012-06-28 3:38 ` Zhao Chenhui
2012-06-28 10:50 ` Benjamin Herrenschmidt
2012-06-28 18:30 ` Kumar Gala [this message]
2012-06-29 10:33 ` Zhao Chenhui-B35336
2012-07-02 10:44 ` Zhao Chenhui
2012-06-29 15:39 ` Tabi Timur-B04825
2012-06-29 15:57 ` Scott Wood
2012-06-29 16:04 ` Timur Tabi
2012-06-29 16:10 ` Scott Wood
2012-06-29 16:12 ` Timur Tabi
2012-06-29 17:10 ` Scott Wood
2012-07-02 10:10 ` Zhao Chenhui
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