From patchwork Wed May 18 18:29:46 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Emilio Cota X-Patchwork-Id: 9121661 Return-Path: X-Original-To: patchwork-qemu-devel@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id B27C79F1D3 for ; Wed, 18 May 2016 18:30:22 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id A88242035E for ; Wed, 18 May 2016 18:30:21 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 9D47720340 for ; Wed, 18 May 2016 18:30:19 +0000 (UTC) Received: from localhost ([::1]:46528 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1b36Ec-0007XQ-Pg for patchwork-qemu-devel@patchwork.kernel.org; Wed, 18 May 2016 14:30:18 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:49202) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1b36EO-0007Vp-Ai for qemu-devel@nongnu.org; Wed, 18 May 2016 14:30:05 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1b36EK-0005kP-87 for qemu-devel@nongnu.org; Wed, 18 May 2016 14:30:03 -0400 Received: from out5-smtp.messagingengine.com ([66.111.4.29]:42142) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1b36EH-0005iC-QJ for qemu-devel@nongnu.org; Wed, 18 May 2016 14:30:00 -0400 Received: from compute5.internal (compute5.nyi.internal [10.202.2.45]) by mailout.nyi.internal (Postfix) with ESMTP id 88707219E8 for ; Wed, 18 May 2016 14:29:46 -0400 (EDT) Received: from frontend2 ([10.202.2.161]) by compute5.internal (MEProxy); Wed, 18 May 2016 14:29:46 -0400 DKIM-Signature: v=1; a=rsa-sha1; c=relaxed/relaxed; d=braap.org; h=cc :content-transfer-encoding:content-type:date:from:in-reply-to :message-id:mime-version:references:subject:to:x-sasl-enc :x-sasl-enc; s=mesmtp; bh=r047X53v+HXiaj9YpaEsPK2savE=; b=G5asaS mVbQi1oABgPEVI3B508q0FWZNSZyKPgj2+NofdT8jpGqr+11QXUAXAz8YcZwuaSE F3CQB9vWKJPMxisNmrvClQAQAFWAlksie7u6IILHqlXkcFC3W48v0M5Gc7vFVGSa fXtb4vHRi5gbktAaWhKM0QJt5QduaXGRRwm5Q= DKIM-Signature: v=1; a=rsa-sha1; c=relaxed/relaxed; d= messagingengine.com; h=cc:content-transfer-encoding:content-type :date:from:in-reply-to:message-id:mime-version:references :subject:to:x-sasl-enc:x-sasl-enc; s=smtpout; bh=r047X53v+HXiaj9 YpaEsPK2savE=; b=CbXF5PvM+WEmisPpyjsmHj9q1oN+p5DRrsonXBO1dYD4/H1 ffQwtqSRVEI3tw1mHIzDyk0m4OqbOhNjsd+B/3np+kFGaf105CMSbDgAjNwolFRI R2PRK9P7UCw4kdNGdvV7w8djWmKxUBHOlBjIxL7I8dzckykfReqMgv4Wr/dE= X-Sasl-enc: aCEqsAgRt3QoRDO+ax6OqYaty3yPhAGqvamt+gVB2eCl 1463596186 Received: from localhost (flamenco.cs.columbia.edu [128.59.20.216]) by mail.messagingengine.com (Postfix) with ESMTPA id 44577680089; Wed, 18 May 2016 14:29:46 -0400 (EDT) Date: Wed, 18 May 2016 14:29:46 -0400 From: "Emilio G. Cota" To: Sergey Fedorov Message-ID: <20160518182946.GA8386@flamenco> References: <1463196873-17737-1-git-send-email-cota@braap.org> <1463196873-17737-5-git-send-email-cota@braap.org> <573CAACC.7060902@gmail.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <573CAACC.7060902@gmail.com> User-Agent: Mutt/1.5.23 (2014-03-12) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 66.111.4.29 Subject: Re: [Qemu-devel] [PATCH v5 04/18] include/processor.h: define cpu_relax() X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: MTTCG Devel , Peter Crosthwaite , QEMU Developers , Paolo Bonzini , Alex =?iso-8859-1?Q?Benn=E9e?= , Richard Henderson Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" X-Spam-Status: No, score=-6.8 required=5.0 tests=BAYES_00,DKIM_SIGNED, RCVD_IN_DNSWL_HI, T_DKIM_INVALID, UNPARSEABLE_RELAY autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP On Wed, May 18, 2016 at 20:47:56 +0300, Sergey Fedorov wrote: > Why don't do like this: > > #if defined(__foo__) > # define ... > #elif defined(__bar__) > # define ... > #else > # define ... > #endif Good point. Changed to: commit ad31d6cff8e309e41bd4bed110f173e473c27c5a Author: Emilio G. Cota Date: Wed Apr 6 18:21:08 2016 -0400 include/processor.h: define cpu_relax() Taken from the linux kernel. Reviewed-by: Richard Henderson Reviewed-by: Alex Bennée Signed-off-by: Emilio G. Cota diff --git a/include/qemu/processor.h b/include/qemu/processor.h new file mode 100644 index 0000000..42bcc99 --- /dev/null +++ b/include/qemu/processor.h @@ -0,0 +1,30 @@ +/* + * Copyright (C) 2016, Emilio G. Cota + * + * License: GNU GPL, version 2. + * See the COPYING file in the top-level directory. + */ +#ifndef QEMU_PROCESSOR_H +#define QEMU_PROCESSOR_H + +#include "qemu/atomic.h" + +#if defined(__i386__) || defined(__x86_64__) +# define cpu_relax() asm volatile("rep; nop" ::: "memory") + +#elif defined(__ia64__) +# define cpu_relax() asm volatile("hint @pause" ::: "memory") + +#elif defined(__aarch64__) +# define cpu_relax() asm volatile("yield" ::: "memory") + +#elif defined(__powerpc64__) +/* set Hardware Multi-Threading (HMT) priority to low; then back to medium */ +# define cpu_relax() asm volatile("or 1, 1, 1;" + "or 2, 2, 2;" ::: "memory") + +#else +# define cpu_relax() barrier() +#endif + +#endif /* QEMU_PROCESSOR_H */