From: Andi Kleen <andi@firstfloor.org>
To: Len Brown <lenb@kernel.org>
Cc: Andi Kleen <andi@firstfloor.org>,
Andika Triwidada <andika@gmail.com>,
linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org
Subject: Re: CPU offline but power consumption increased?
Date: Tue, 10 Apr 2007 15:44:58 +0200 [thread overview]
Message-ID: <20070410134458.GA723@one.firstfloor.org> (raw)
In-Reply-To: <200704100413.51637.lenb@kernel.org>
> Speaking for all Intel hardware implemented from pre-history until now,
> deep C-states is the best you can do, and there is no special offline
> mode to save more power.
We don't use deep c states currently; just HLT.
Right now it doesn't make much difference because no multi socket
servers do deep C states and secondary cores can normally not go
deep on their own; but if any of this changes this code would
need to be fixed.
But cpu off line is really a special case -- maybe it is even
possible to do something better on current hardware.
> and if the BIOS is implemented properly, the core will be spinning in the
> deepest available C-state. Of course, it would probably be more interesting
> to simply leave the core on-line and let it go idle...
I don't see any BIOS call in play_dead()
-Andi
prev parent reply other threads:[~2007-04-10 13:45 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-04-07 4:23 CPU offline but power consumption increased? Andika Triwidada
2007-04-07 23:38 ` Andi Kleen
2007-04-10 8:13 ` Len Brown
2007-04-10 13:44 ` Andi Kleen [this message]
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