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Date: Tue, 14 Jan 2014 08:36:16 -0600
From: Steven Pratt <slpratt@austin.ibm.com>
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To: linuxppc-dev@lists.ozlabs.org
Subject: Disable sleep states on P7+
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I am looking for info on when and how we are able to disable power saving features of current (P7, P7+) chips in order to reduce latency. This is often done in latency sensitive applications when power consumption is not an issue. On Intel boxes we can disable P-state frequency changes as well as disabling C-State or sleep state changes. In fact we can control how deep a sleep the processor can go into.  I know we have control Dynamic Processor Scaling and Idle Power Savings, but what states do these really affect?  Can I really disable Nap mode of a processor? If so how?  Can I disable even the lightest winkle mode?  Looking for current information (read RHEL 6 and SLES11), future changes are interesting.

Steve