From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wg0-f42.google.com (mail-wg0-f42.google.com [74.125.82.42]) by dpdk.org (Postfix) with ESMTP id 69E94804A for ; Tue, 9 Dec 2014 09:53:20 +0100 (CET) Received: by mail-wg0-f42.google.com with SMTP id z12so182006wgg.29 for ; Tue, 09 Dec 2014 00:53:20 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:message-id:date:from:user-agent:mime-version:to :cc:subject:references:in-reply-to:content-type :content-transfer-encoding; bh=SnGuJaKR6tAC9Ng+2lfJXfAJ1LGoUmR8BHhXPvFDbQg=; b=AAeXDyOIWBWPWtBHYCRTY5XOvFSHZS30Elnv+eUSYNa9EMGG8co857srYOMwKUkkW5 bHKZCT3Vz6euS+/1+JlXo+czTztisPazmhVpiq1VYdGrXihYaCVfPuEInQkuGlVmWnqc wqvFXeBj3tSIiRbUOPQVrLlt7CkzF8WXNuGp+8sw+jvpXVuK55+hmpD0LWvV/+Pj3x64 S2BSikpOmuYmEnT/Grh+bVtN+ECTFD3CSGD3ghvrpmiIc8YcLSpPAVgXP81PnzrBFQWZ 394GMX1DrnoloBFHulYWGkZETvJFjCFonCAy6LTfmpxY0UcTAMucLZv01VHksBXbGhCa QQ+w== X-Gm-Message-State: ALoCoQngc9ba6irg81UGup8PpyXRQJH+8ac4tiThuYVLnXr0cTnX7OejJdO8A9nU20inbxkXL4r/ X-Received: by 10.180.93.167 with SMTP id cv7mr2577513wib.12.1418115199567; Tue, 09 Dec 2014 00:53:19 -0800 (PST) Received: from [10.16.0.195] (guy78-3-82-239-227-177.fbx.proxad.net. [82.239.227.177]) by mx.google.com with ESMTPSA id o2sm799086wja.45.2014.12.09.00.53.18 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Tue, 09 Dec 2014 00:53:19 -0800 (PST) Message-ID: <5486B87E.5010404@6wind.com> Date: Tue, 09 Dec 2014 09:53:18 +0100 From: Olivier MATZ User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Icedove/24.5.0 MIME-Version: 1.0 To: Neil Horman , Jia Yu References: <1415381289-43291-1-git-send-email-jyu@vmware.com> <20141208150401.GB3907@localhost.localdomain> In-Reply-To: <20141208150401.GB3907@localhost.localdomain> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: dev@dpdk.org Subject: Re: [dpdk-dev] lib: include rte_memory.h for __rte_cache_aligned X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 09 Dec 2014 08:53:20 -0000 Hi Neil, On 12/08/2014 04:04 PM, Neil Horman wrote: > On Fri, Nov 07, 2014 at 09:28:09AM -0800, Jia Yu wrote: >> Include rte_memory.h for lib files that use __rte_cache_aligned >> attribute. >> >> Signed-off-by: Jia Yu >> > Why? I presume there was a build break or something. Please repost with a > changelog that details what this patch is for. > Neil I don't know if Yu's issue was the same, but I had a very "fun" issue with __rte_cache_aligned in my application. Consider the following code: struct per_core_foo { ... } __rte_cache_aligned; struct global_foo { struct per_core_foo foo[RTE_MAX_CORE]; }; If __rte_cache_aligned is not defined (rte_memory.h is not included), the code compiles but the structure is not aligned... it defines the structure and creates a global variable called __rte_cache_aligned. And this can lead to really bad things if this code is in a .h that is included by files that may or may not include rte_memory.h I have no idea about how we could prevent this issue, except using __attribute__((aligned(CACHE_LINE))) instead of __rte_cache_aligned. Anyway this could probably explain the willing to include rte_memory.h everywhere. Regards, Olivier