From mboxrd@z Thu Jan 1 00:00:00 1970 From: Juergen Gross Subject: Re: [PATCH] use per-cpu variables in cpufreq Date: Fri, 27 May 2011 15:29:17 +0200 Message-ID: <4DDFA72D.2060806@ts.fujitsu.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Keir Fraser Cc: xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org On 05/27/11 15:11, Keir Fraser wrote: > On 27/05/2011 12:11, "Juergen Gross" wrote: > >> The cpufreq driver used some local arrays indexed by cpu number. This patch >> replaces those arrays by per-cpu variables. The AMD and INTEL specific parts >> used different per-cpu data structures with nearly identical semantics. >> Fold the two structures into one by adding a generic architecture data item. > Xen's per-cpu data gets freed across cpu offline/online, whereas cpu-indexed > arrays of course do not. Will the cpufreq state be correctly handled across > offline/online if we switch to per-cpu vars? As far as I could see, yes. The data should only be used for cpus with a valid acpid->cpuid translation, which is created when a cpu is going online and destroyed when it is going offline again. It would be nice, however, if the INTEL and/or AMD code owners could give an ack on this... Juergen -- Juergen Gross Principal Developer Operating Systems TSP ES&S SWE OS6 Telephone: +49 (0) 89 3222 2967 Fujitsu Technology Solutions e-mail: juergen.gross@ts.fujitsu.com Domagkstr. 28 Internet: ts.fujitsu.com D-80807 Muenchen Company details: ts.fujitsu.com/imprint.html