From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wg0-f54.google.com (mail-wg0-f54.google.com [74.125.82.54]) by dpdk.org (Postfix) with ESMTP id 793E37F14 for ; Wed, 17 Dec 2014 14:02:06 +0100 (CET) Received: by mail-wg0-f54.google.com with SMTP id l2so20272955wgh.41 for ; Wed, 17 Dec 2014 05:02:06 -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=0uDUPrSa7ChJYhuualZSw4JBAXnMWwdkKYV10kVeaio=; b=NKwiXBXbYsazybyOXWuOaeoxXDkh2owz9fpQAnoHpBnbIBBGcigwXZWT2bkMWKiyAT 8AkGJXXcxnyZ6oPB3893igtcIzQTDy8jFIIUfImSDg/LOj8pY9x/uYMFMVpfx6jwy4tc o03RbsOt6UtGME0LNXxux6hLaFeEYbnPoPmaPspIBx3B5XGwep4U5xv1bR46Htyg6kd+ C6wJXnqRc9hSEK0B/m1RphHXvzjo9ku32OW1uQRf9CzXP9FNO8uPNRV+Bk+xq+LD4ydv BgrAU5Kt9UpIptorUKU4/Ixr/yYhjNhGgPbTZ/0mLkJtCfkrp/MVXXgnHpRK2lVOLT4o Z+GA== X-Gm-Message-State: ALoCoQmeplTXcLXOP/AVn/5vbNwhL8/b5fKhsBXeA9yZgaQBEOw9qjEbqegQTgXEfnIzJrqvbh3b X-Received: by 10.194.2.34 with SMTP id 2mr58126642wjr.58.1418821326288; Wed, 17 Dec 2014 05:02:06 -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 c10sm5055274wjy.4.2014.12.17.05.02.05 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 17 Dec 2014 05:02:05 -0800 (PST) Message-ID: <54917ECB.3080404@6wind.com> Date: Wed, 17 Dec 2014 14:02:03 +0100 From: Olivier MATZ User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Icedove/31.2.0 MIME-Version: 1.0 To: Helmut Sim , Alex Markuze References: In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Cc: "dev@dpdk.org" Subject: Re: [dpdk-dev] two tso related questions 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: Wed, 17 Dec 2014 13:02:06 -0000 Hi Helmut, On 12/17/2014 08:17 AM, Helmut Sim wrote: >>>>> While working on TSO based solution I faced the following two questions: >>>>> >>>>> 1. >>>>> is there a maximum pkt_len to be used with TSO?, e.g. let's say if >>>>> seg_sz >>>>> is 1400 can the entire segmented pkt be 256K (higer than 64K) ?, then >>>>> the >>>>> driver gets a list of chanined mbufs while the first mbuf is set to TSO >>>>> offload. I think the limitations depend on: - the window size advertised by the peer: your stack should handle this and not generate more packets that what the peer can receive - the driver: on ixgbe, the maximum payload length is 2^18. I don't know if there is a limitation on number of chained descriptors. I think we should define a way to know this limitation in the API. Maybe a comment saying that the TSO length should not be higher than 256KB (or fix it to 64KB in case future drivers do not support 256KB) is enough. Regards, Olivier