From owner-svn-src-all@FreeBSD.ORG  Thu Apr 14 16:53:32 2011
Return-Path: <owner-svn-src-all@FreeBSD.ORG>
Delivered-To: svn-src-all@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34])
	by hub.freebsd.org (Postfix) with ESMTP id 6E992106566B;
	Thu, 14 Apr 2011 16:53:32 +0000 (UTC)
	(envelope-from jkim@FreeBSD.org)
Received: from svn.freebsd.org (svn.freebsd.org [IPv6:2001:4f8:fff6::2c])
	by mx1.freebsd.org (Postfix) with ESMTP id 5CF278FC13;
	Thu, 14 Apr 2011 16:53:32 +0000 (UTC)
Received: from svn.freebsd.org (localhost [127.0.0.1])
	by svn.freebsd.org (8.14.3/8.14.3) with ESMTP id p3EGrWM3041067;
	Thu, 14 Apr 2011 16:53:32 GMT (envelope-from jkim@svn.freebsd.org)
Received: (from jkim@localhost)
	by svn.freebsd.org (8.14.3/8.14.3/Submit) id p3EGrWmv041064;
	Thu, 14 Apr 2011 16:53:32 GMT (envelope-from jkim@svn.freebsd.org)
Message-Id: <201104141653.p3EGrWmv041064@svn.freebsd.org>
From: Jung-uk Kim <jkim@FreeBSD.org>
Date: Thu, 14 Apr 2011 16:53:32 +0000 (UTC)
To: src-committers@freebsd.org, svn-src-all@freebsd.org,
	svn-src-head@freebsd.org
X-SVN-Group: head
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Cc: 
Subject: svn commit: r220631 - in head/sys: amd64/include i386/include
X-BeenThere: svn-src-all@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: "SVN commit messages for the entire src tree \(except for &quot;
	user&quot; and &quot; projects&quot; \)" <svn-src-all.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/svn-src-all>,
	<mailto:svn-src-all-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/svn-src-all>
List-Post: <mailto:svn-src-all@freebsd.org>
List-Help: <mailto:svn-src-all-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/svn-src-all>,
	<mailto:svn-src-all-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Thu, 14 Apr 2011 16:53:32 -0000

Author: jkim
Date: Thu Apr 14 16:53:32 2011
New Revision: 220631
URL: http://svn.freebsd.org/changeset/base/220631

Log:
  Add a function rdtsc32() to read lower 32 bits from TSC and discard upper
  32 bits.  Some times compiler inserts unnecessary instructions to preserve
  unused upper 32 bits even when it is casted to a 32-bit value.  It reduces
  such compiler mistakes where every cycle counts.

Modified:
  head/sys/amd64/include/cpufunc.h
  head/sys/i386/include/cpufunc.h

Modified: head/sys/amd64/include/cpufunc.h
==============================================================================
--- head/sys/amd64/include/cpufunc.h	Thu Apr 14 16:45:16 2011	(r220630)
+++ head/sys/amd64/include/cpufunc.h	Thu Apr 14 16:53:32 2011	(r220631)
@@ -322,6 +322,15 @@ rdtsc(void)
 	return (low | ((uint64_t)high << 32));
 }
 
+static __inline uint32_t
+rdtsc32(void)
+{
+	uint32_t rv;
+
+	__asm __volatile("rdtsc" : "=a" (rv) : : "edx");
+	return (rv);
+}
+
 static __inline void
 wbinvd(void)
 {

Modified: head/sys/i386/include/cpufunc.h
==============================================================================
--- head/sys/i386/include/cpufunc.h	Thu Apr 14 16:45:16 2011	(r220630)
+++ head/sys/i386/include/cpufunc.h	Thu Apr 14 16:53:32 2011	(r220631)
@@ -332,6 +332,15 @@ rdtsc(void)
 	return (rv);
 }
 
+static __inline uint32_t
+rdtsc32(void)
+{
+	uint32_t rv;
+
+	__asm __volatile("rdtsc" : "=a" (rv) : : "edx");
+	return (rv);
+}
+
 static __inline void
 wbinvd(void)
 {