From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:46300) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bBNOp-0003ec-SW for qemu-devel@nongnu.org; Fri, 10 Jun 2016 10:27:04 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bBNOk-0005gN-7P for qemu-devel@nongnu.org; Fri, 10 Jun 2016 10:27:02 -0400 Received: from mail-pf0-x242.google.com ([2607:f8b0:400e:c00::242]:34847) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bBNOk-0005gA-1O for qemu-devel@nongnu.org; Fri, 10 Jun 2016 10:26:58 -0400 Received: by mail-pf0-x242.google.com with SMTP id t190so5238235pfb.2 for ; Fri, 10 Jun 2016 07:26:57 -0700 (PDT) Sender: Richard Henderson From: Richard Henderson Date: Fri, 10 Jun 2016 07:26:42 -0700 Message-Id: <1465568813-19771-5-git-send-email-rth@twiddle.net> In-Reply-To: <1465568813-19771-1-git-send-email-rth@twiddle.net> References: <1465568813-19771-1-git-send-email-rth@twiddle.net> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Subject: [Qemu-devel] [PULL 04/15] include/processor.h: define cpu_relax() List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: peter.maydell@linaro.org, "Emilio G. Cota" From: "Emilio G. Cota" Taken from the linux kernel. Reviewed-by: Sergey Fedorov Reviewed-by: Richard Henderson Reviewed-by: Alex Bennée Signed-off-by: Emilio G. Cota Message-Id: <1465412133-3029-5-git-send-email-cota@braap.org> Signed-off-by: Richard Henderson --- include/qemu/processor.h | 30 ++++++++++++++++++++++++++++++ 1 file changed, 30 insertions(+) create mode 100644 include/qemu/processor.h 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 */ -- 2.5.5