From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arjan van de Ven Subject: Re: cpuidle asymmetry (was Re: [RFC PATCH V4 5/5] cpuidle: cpuidle driver for apm) Date: Fri, 01 Apr 2011 07:38:23 -0700 Message-ID: <4D95E35F.2080707@linux.intel.com> References: <20110322123336.28725.29810.stgit@tringupt.in.ibm.com> <20110323121458.ec7cdaf9.sfr@canb.auug.org.au> <4D89CA7D.8080108@linux.vnet.ibm.com> <4D8B550D.5000409@linux.vnet.ibm.com> <20110325180156.GC19214@dirshya.in.ibm.com> <1301577536.4859.249.camel@twins> <20110401081522.GA22339@in.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20110401081522.GA22339@in.ibm.com> Sender: linux-kernel-owner@vger.kernel.org To: dipankar@in.ibm.com Cc: Len Brown , Peter Zijlstra , Vaidyanathan Srinivasan , Trinabh Gupta , Stephen Rothwell , suresh.b.siddha@intel.com, benh@kernel.crashing.org, venki@google.com, ak@linux.intel.com, linux-kernel@vger.kernel.org, xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org On 4/1/2011 1:15 AM, Dipankar Sarma wrote: > On Fri, Apr 01, 2011 at 12:09:25AM -0400, Len Brown wrote: >>>> Moorestown is already an example of an asymmetric system, >>>> since its deepest c-state is available on cpu0, but not on cpu1. >>>> So it needs different tables for each cpu. >>> wtf are these hardware guys smoking and how the heck are we supposed to >>> schedule on such a machine? Prefer to keep cpu1 busy while idling cpu0? >> they are smoking micro-amps:-) >> >> S0i3 on cpu0 can be entered only after cpu1 is already off-line, >> among other system hardware dependencies... >> >> So it makes no sense to export S0i3 as a c-state on cpu1. >> >> When cpu1 is online, the scheduler treats it as a normal SMP. > Isn't S0i3 a "system" state, as opposed to cpu state ? it's misnamed. it's a C state to the OS.