From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Wes Felter <wmf@austin.ibm.com>
Cc: Linux Kernel list <linux-kernel@vger.kernel.org>
Subject: Re: SMP cpu deep sleep
Date: Sat, 21 Aug 2004 10:53:45 +1000 [thread overview]
Message-ID: <1093049624.9932.262.camel@gaston> (raw)
In-Reply-To: <pan.2004.08.20.16.44.39.888193@austin.ibm.com>
On Sat, 2004-08-21 at 02:44, Wes Felter wrote:
> The CPU hotplug patch is the way to go, but the hardware is the problem. I
> talked to an Intel CPU architect at MICRO last year and he confirmed that
> SMP Intel systems don't support any low-power modes besides HLT. AMD's
> documentation says that Opterons support voltage/frequency scaling (aka
> Cool 'n' Quiet), but AFAICT the documentation is wrong. In summary, you
> are doomed.
Well, with intel CPUs maybe ;) On PPC we can put some CPUs (at least the
desktop ones and the 970, I don't know about POWER3/4/5) into SLEEP mode
after flushing all caches & masking all IRQs to them, and get them out
via an IPI, or we can mask EE as well and get them out via a soft reset
if we have access to it.
Ben.
next prev parent reply other threads:[~2004-08-21 1:04 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-08-20 8:06 SMP cpu deep sleep Hans Kristian Rosbach
2004-08-20 8:58 ` Jeff Sipek
2004-08-20 9:42 ` Hans Kristian Rosbach
2004-08-20 14:38 ` Zwane Mwaikambo
2004-08-20 16:44 ` Wes Felter
2004-08-21 0:53 ` Benjamin Herrenschmidt [this message]
2004-08-23 21:30 ` Bill Davidsen
2004-08-28 19:15 ` Alan Cox
2004-08-24 22:48 ` Pavel Machek
-- strict thread matches above, loose matches on Subject: below --
2004-08-20 14:30 Nakajima, Jun
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