From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from dpdk.org (dpdk.org [92.243.14.124]) by inbox.dpdk.org (Postfix) with ESMTP id A12F0A317C for ; Thu, 17 Oct 2019 17:14:50 +0200 (CEST) Received: from [92.243.14.124] (localhost [127.0.0.1]) by dpdk.org (Postfix) with ESMTP id 8019A1E8F4; Thu, 17 Oct 2019 17:14:49 +0200 (CEST) Received: from mail-pf1-f194.google.com (mail-pf1-f194.google.com [209.85.210.194]) by dpdk.org (Postfix) with ESMTP id 3E5A11E8EF for ; Thu, 17 Oct 2019 17:14:47 +0200 (CEST) Received: by mail-pf1-f194.google.com with SMTP id 205so1865838pfw.2 for ; Thu, 17 Oct 2019 08:14:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=networkplumber-org.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=38lmrroZ/8O+OkQVlXIiGU+ZmpHSUoTVAWa4eWgHB+c=; b=RnNsLZEhEBEXFkwMrkoL8xKRfdx+4fcxVkrmMLuS2XcVgg8pdklxUZ5XKQXxLz8xRk PW8Hvx4sP6h10WmiCqvtCCHbMTGkgA8aqoMGJc7KP4GdwQdcI/Vpsy4e/wXyLRxpQSAo 4SPKSohMqp5VSb5//6D9kPLVkXPqwQX0XKVF/7VWgVcs1fYS7i/v0eiW7LkhcyIgoK0X fJSWslW+lbAMnGeqxXmJ6wTDDEz0kvH227GofkPT0w8i+jHCogV6qwk5kq+Azd6ZRePs m8DQizOYszjxgg3yP56VLVTdQf127p1jb8PCIsw8tMwQLU18qgXlaiY+xZU4zPe+Ao4U XSOA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=38lmrroZ/8O+OkQVlXIiGU+ZmpHSUoTVAWa4eWgHB+c=; b=Xv6+iTVHtLudzh3hCARXoVgg/z3brqclG+ItVOhMjArskkin1dBYXncwFL9k+v3Ilg MH8tz+4SxXf2xyuIyIX5lqd5G4c/nQ4cdZB6RcWipYjQGAfvD6kHC7R9jyt46mFXW64p sWpo7SFceNqxIrXeATW3EUqxW/lmzWt+jUDtBxssq+WjpKP6eOHydiOPyZATwe3eJoFK AfKRWvfuS31L98XILxKeW+HFxBlenVLjP4OaSNPmENmAZcPRNCGCoxBuvDWipRlnAD6O KCHjuS4UaDipW+LwTdsitxlSkgX96tTDe3H+nyt8qrslxkQXK9J6EiM0eeHSkdmuLhAx 7Cew== X-Gm-Message-State: APjAAAVao9/PrIEpJpePL8pbbbvNJB0oB3YCYlbsIAx7lLyperMmb6MF NcSkghHCJJnkQskwQ+uF+H4KAg== X-Google-Smtp-Source: APXvYqwpWZTnaqFnoyGsVtWQu+ULY9d8tGxCPyXa4jp3u4Ssd1NW4xcKtli5fplTtsJ9qlhV7wk3jA== X-Received: by 2002:a17:90a:304:: with SMTP id 4mr5130358pje.128.1571325286296; Thu, 17 Oct 2019 08:14:46 -0700 (PDT) Received: from hermes.lan (204-195-22-127.wavecable.com. [204.195.22.127]) by smtp.gmail.com with ESMTPSA id w65sm3155454pfb.106.2019.10.17.08.14.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 17 Oct 2019 08:14:46 -0700 (PDT) Date: Thu, 17 Oct 2019 08:14:44 -0700 From: Stephen Hemminger To: Shahaf Shuler Cc: "dev@dpdk.org" , Thomas Monjalon , "olivier.matz@6wind.com" , "wwasko@nvidia.com" , "spotluri@nvidia.com" , Asaf Penso , Slava Ovsiienko Message-ID: <20191017081444.7f91b680@hermes.lan> In-Reply-To: <20191017072723.36509-1-shahafs@mellanox.com> References: <20191017072723.36509-1-shahafs@mellanox.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Subject: Re: [dpdk-dev] [RFC PATCH 20.02] mbuf: hint PMD not to inline packet X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" On Thu, 17 Oct 2019 07:27:34 +0000 Shahaf Shuler wrote: > Some PMDs inline the mbuf data buffer directly to device. This is in > order to save the overhead of the PCI headers involved when the device > DMA read the buffer pointer. For some devices it is essential in order > to reach the pick BW. > > However, there are cases where such inlining is in-efficient. For example > when the data buffer resides on other device memory (like GPU or storage > device). attempt to inline such buffer will result in high PCI overhead > for reading and copying the data from the remote device. > > To support a mixed traffic pattern (some buffers from local DRAM, some > buffers from other devices) with high BW, a hint flag is introduced in > the mbuf. > Application will hint the PMD whether or not it should try to inline the > given mbuf data buffer. PMD should do best effort to act upon this > request. > > Signed-off-by: Shahaf Shuler This kind of optimization is hard, and pushing the problem to the application to decide seems like the wrong step. Can the driver just infer this already because some mbuf's are external?