From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from NAM02-SN1-obe.outbound.protection.outlook.com (mail-sn1nam02on0068.outbound.protection.outlook.com [104.47.36.68]) by dpdk.org (Postfix) with ESMTP id 5E2655684 for ; Sat, 23 Jul 2016 11:36:52 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=CAVIUMNETWORKS.onmicrosoft.com; s=selector1-cavium-com; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version; bh=L1ODvo3vJ0QjvSaPZRck1w/neZsExObRUn33Hf/uOkI=; b=JwfMylcPjO5mJ3VtdVJZN/WC/vNcaOtzFlnfuN5GYb0KFGVFc7yiuOEmXl9IercJmHzLRoZGYU4745bc0MWTVXyzNgKx/t7UeCbgc6XNlE2NiYroxAbfXHOoncboJ2L3fVlw2AiLn1DS6naXk49FZTDkF9F9bPOLF+IRtt2EkI4= Authentication-Results: spf=none (sender IP is ) smtp.mailfrom=Jerin.Jacob@cavium.com; Received: from localhost.localdomain (111.93.218.67) by BLUPR0701MB1715.namprd07.prod.outlook.com (10.163.85.141) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384_P384) id 15.1.544.10; Sat, 23 Jul 2016 09:36:46 +0000 Date: Sat, 23 Jul 2016 15:06:22 +0530 From: Jerin Jacob To: Thomas Monjalon CC: Juhamatti Kuusisaari , "dev@dpdk.org" , "Ananyev, Konstantin" Message-ID: <20160723093621.GA18376@localhost.localdomain> References: <20160715043951.32040-1-juhamatti.kuusisaari@coriant.com> <2601191342CEEE43887BDE71AB97725836B7E32F@irsmsx105.ger.corp.intel.com> <14017551.U6D1dIIx0P@xps13> <20160723060515.GA13747@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; 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This is not guaranteed with a read barrier, > >> > > changed to a write barrier just before tail update which in practice guarantees correct order of reads and writes. > >> > > > >> > > Signed-off-by: Juhamatti Kuusisaari > >> > > >> > Acked-by: Konstantin Ananyev > >> > >> Applied, thanks > > > > There was ongoing discussion on this > > http://dpdk.org/ml/archives/dev/2016-July/044168.html > > Sorry Jerin, I forgot this email. > The problem is that nobody replied to your email and you did not nack > the v2 of this patch. > > > This change may not be required as it has the performance impact. > > We need to clearly understand what is the performance impact > (numbers and use cases) on one hand, and is there a real bug fixed > by this patch on the other hand? IHMO, there is no real bug here. rte_smb_rmb() provides the LOAD-STORE barrier to make sure tail pointer WRITE happens only after prior LOADS. Thoughts? > > Please guys make things clear and we'll revert if needed.