From owner-svn-src-head@FreeBSD.ORG Tue Dec 10 20:25:44 2013 Return-Path: Delivered-To: svn-src-head@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 940F1D77; Tue, 10 Dec 2013 20:25:44 +0000 (UTC) Received: from svn.freebsd.org (svn.freebsd.org [IPv6:2001:1900:2254:2068::e6a:0]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.freebsd.org (Postfix) with ESMTPS id 80BAF1DA5; Tue, 10 Dec 2013 20:25:44 +0000 (UTC) Received: from svn.freebsd.org ([127.0.1.70]) by svn.freebsd.org (8.14.7/8.14.7) with ESMTP id rBAKPinp005302; Tue, 10 Dec 2013 20:25:44 GMT (envelope-from mav@svn.freebsd.org) Received: (from mav@localhost) by svn.freebsd.org (8.14.7/8.14.7/Submit) id rBAKPiNh005301; Tue, 10 Dec 2013 20:25:44 GMT (envelope-from mav@svn.freebsd.org) Message-Id: <201312102025.rBAKPiNh005301@svn.freebsd.org> From: Alexander Motin Date: Tue, 10 Dec 2013 20:25:44 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r259197 - head/sys/x86/cpufreq X-SVN-Group: head MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.17 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 10 Dec 2013 20:25:44 -0000 Author: mav Date: Tue Dec 10 20:25:43 2013 New Revision: 259197 URL: http://svnweb.freebsd.org/changeset/base/259197 Log: Do not DELAY() for P-state transition unless we want to see the result. Intel manual says: "If a transition is already in progress, transition to a new value will subsequently take effect. Reads of IA32_PERF_CTL determine the last targeted operating point." So seems it should be fine to just trigger wanted transition and go. Linux does the same. MFC after: 1 month Modified: head/sys/x86/cpufreq/est.c Modified: head/sys/x86/cpufreq/est.c ============================================================================== --- head/sys/x86/cpufreq/est.c Tue Dec 10 20:09:49 2013 (r259196) +++ head/sys/x86/cpufreq/est.c Tue Dec 10 20:25:43 2013 (r259197) @@ -1288,10 +1288,9 @@ est_set_id16(device_t dev, uint16_t id16 msr = (msr & ~0xffff) | id16; wrmsr(MSR_PERF_CTL, msr); - /* Wait a short while for the new setting. XXX Is this necessary? */ - DELAY(EST_TRANS_LAT); - if (need_check) { + /* Wait a short while and read the new status. */ + DELAY(EST_TRANS_LAT); est_get_id16(&new_id16); if (new_id16 != id16) { if (bootverbose)