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Subject: Re: [PATCH] Donate dedicated CPU cycles
From: Jake Moilanen <moilanen@austin.ibm.com>
To: Paul Mackerras <paulus@samba.org>
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Date: Thu, 07 Jun 2007 16:24:11 -0500
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On Wed, 2007-06-06 at 14:25 +1000, Paul Mackerras wrote:
> Jake Moilanen writes:
> 
> > A Power6 can give up CPU cycles on a dedicated CPU (as opposed to a
> > shared CPU) to other shared processors if the administrator asks for it
> > (via the HMC).
> > 
> > This patch enables that to work properly on P6.
> 
> Is this something that needs to be controlled from userland, e.g. by a
> sysctl or something in /sys?

The turning on of donating of dedicated CPU cycles is done via the HMC.
IHMO, it would be a bit redundant to do it in two places.

The reason why this is better than just shared processors is the
partitions w/ dedicated CPUs are guaranteed an actual processor, yet the
system is still able to increase the capacity of the shared CPU pool.

I have an updated patch come w/ a rename of the VPA field.

Jake