From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.1 required=3.0 tests=DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,T_DKIM_INVALID, URIBL_BLOCKED,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E47EBC3279B for ; Fri, 6 Jul 2018 09:40:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8839223FE1 for ; Fri, 6 Jul 2018 09:40:27 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="mvg5kyk1" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8839223FE1 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753596AbeGFJkY (ORCPT ); Fri, 6 Jul 2018 05:40:24 -0400 Received: from merlin.infradead.org ([205.233.59.134]:41506 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753281AbeGFJkW (ORCPT ); Fri, 6 Jul 2018 05:40:22 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=FvrJgYCNVm63G4YkPJd5KxHy3P3Q6xrdfoHoovO4fXs=; b=mvg5kyk1pD1gcOkHpvevH/LJa YPRSQ+T7WXkdLhAsCcGVB+KjtvrWGgTQ099eFx2emHcA88QkW2s7OTvNXwfkyNqRypYZw+Z+QdLoD 9D8EYGVl4uz24sh1QZEuoX1qQwP8RJVUyznAYDkt2RjZlwDL8FuOmpjCJG/kSefrHhWxFTUZXtUJG VmTcWg4g6cziGahFs2xJ3FuuAaljetRn8BJ9p4ztr6DZn+jO+G2eWqx0iSHsV6W95O0adz7RjHzeq g9JlvAlUme1U5a1p9Ap1f2iv1PaT8hFOo0sdDLs1X+AXcjnmGbKbF9ahjKf8jKhW9Nt5Qq9Kl4MQY 5d5zO1SIA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1fbNDD-00089N-8T; Fri, 06 Jul 2018 09:39:35 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 64B812028932E; Fri, 6 Jul 2018 11:39:32 +0200 (CEST) Date: Fri, 6 Jul 2018 11:39:32 +0200 From: Peter Zijlstra To: Guo Ren Cc: linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, tglx@linutronix.de, daniel.lezcano@linaro.org, jason@lakedaemon.net, arnd@arndb.de, c-sky_gcc_upstream@c-sky.com, gnu-csky@mentor.com, thomas.petazzoni@bootlin.com, wbx@uclibc-ng.org, green.hu@gmail.com, Will Deacon Subject: Re: [PATCH V2 16/19] csky: SMP support Message-ID: <20180706093932.GT2476@hirez.programming.kicks-ass.net> References: <21d859826fe19aecaa2aefe3103d6d33e6f1b925.1530465326.git.ren_guo@c-sky.com> <20180705180503.GH2530@hirez.programming.kicks-ass.net> <20180706060740.GB8707@guoren> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180706060740.GB8707@guoren> User-Agent: Mutt/1.10.0 (2018-05-17) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jul 06, 2018 at 02:07:40PM +0800, Guo Ren wrote: > > Please explain those mb()'s... I'm thinking you meant to use smp_mb(). > Yes, smp_mb(). Current smp_mb()&mb() is the same: sync.is. > > In next version patch, I'll seperate smp_mb() and mb() and use ld/st.barrier > instead of sync.is. Sync.is is expensive that it flush cpu's pipeline. I'll second my own call for documentation, because now there's three memory ordering instructions: "SYNC", "SYNC.IS" and "LD/ST.BARRIER" None of which have yet been explained.