From: Li Yang <leoli@freescale.com>
To: Pavel Machek <pavel@ucw.cz>
Cc: linux-kernel@vger.kernel.org
Subject: Re: nonboot cpu on SMP suspend
Date: Mon, 23 Mar 2009 15:15:57 +0800 [thread overview]
Message-ID: <2a27d3730903230015h6cc320bek423764eb496d6b30@mail.gmail.com> (raw)
In-Reply-To: <20090320185851.GB1418@ucw.cz>
On Sat, Mar 21, 2009 at 2:58 AM, Pavel Machek <pavel@ucw.cz> wrote:
> On Wed 2009-03-18 14:25:32, Li Yang wrote:
>> Hi all,
>>
>> I'm curious why we need to un-plug all the nonboot cpus before suspend
>> and start them all over again after the suspend(ACPI sleep)? I mean
>> if we can bring the booting cpu back to the exact state as before
>> suspend, why can't we just do the same for non-booting cpus? And that
>> will be much faster. Any thought? Thanks.
>
> Why do you think it will be faster?
_cpu_down() and _cpu_up() are surely complex functions, involving
work_queues and synchronization between boot cpu and non-boot cpu. On
the contrary, to bring the cpu back to previous state is much simpler.
For standby state, you barely need to do anything. For mem state,
you only need to restore the registers and states of the CPU.
- Leo
next prev parent reply other threads:[~2009-03-23 7:16 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-03-18 6:25 nonboot cpu on SMP suspend Li Yang
2009-03-18 23:00 ` Rafael J. Wysocki
2009-03-19 7:04 ` chen gong
2009-03-19 7:18 ` Li Yang
2009-03-19 12:30 ` Rafael J. Wysocki
2009-03-20 18:58 ` Pavel Machek
2009-03-23 7:15 ` Li Yang [this message]
2009-03-23 10:38 ` Pavel Machek
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