From owner-freebsd-net@FreeBSD.ORG Thu Sep 18 14:16:36 2014 Return-Path: Delivered-To: freebsd-net@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 9261A150; Thu, 18 Sep 2014 14:16:36 +0000 (UTC) Received: from mail-qa0-x22d.google.com (mail-qa0-x22d.google.com [IPv6:2607:f8b0:400d:c00::22d]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 2CF67B89; Thu, 18 Sep 2014 14:16:36 +0000 (UTC) Received: by mail-qa0-f45.google.com with SMTP id s7so1143140qap.18 for ; Thu, 18 Sep 2014 07:16:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; bh=9Pvf0pm+/GI60Oo68S0nok3Hq7X+nXfIIFisQBuzJdM=; b=MeTVt9pGNFOvsNHZZ7DFOrFh2N89PG+jqAvtt5r89H52xmZQBkvuj8KzfXugnNtRl4 wvpq4NnrC8L31uZoIN+/vQz9gowvSO+NR2elfQT0TCSeRWO/V4LIIUIA8h4QZskQcytR XtqiZqbJhUi4M4BkEwrhwXbaTm8pdIbyIJsWgDgM+jyrf+1XuRuMhFQ6TKdstwJow+sM Na1sD0E88XZ4xqZ9C+Hn1lPeyx55WnOEOqMnfCpOKXkX7giOc/oyRIxzqSUx9dD+Kzo4 tKHGgMzC57WI5E6tmQ91xqHeE4MQdPVoyoYJcsd/MRvfHaWTKlqfXktj8eJwPE7DGG3U qfog== MIME-Version: 1.0 X-Received: by 10.224.86.5 with SMTP id q5mr9574982qal.36.1411049795051; Thu, 18 Sep 2014 07:16:35 -0700 (PDT) Received: by 10.140.104.241 with HTTP; Thu, 18 Sep 2014 07:16:34 -0700 (PDT) In-Reply-To: <5419EE95.40600@selasky.org> References: <5419EE95.40600@selasky.org> Date: Thu, 18 Sep 2014 16:16:34 +0200 Message-ID: Subject: Re: [RFC] Patch to add Software/Generic Segmentation Offload (GSO) support in FreeBSD From: Stefano Garzarella To: Hans Petter Selasky Content-Type: text/plain; charset=UTF-8 X-Content-Filtered-By: Mailman/MimeDel 2.1.18-1 Cc: "freebsd-net@freebsd.org" , Adrian Chadd , freebsd-current , Luigi Rizzo X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 18 Sep 2014 14:16:36 -0000 Hi Hans, I saw the discussion about TSO, but the GSO is a software implementation unrelated with the hardware. Furthermore, if the TSO is enabled (and supported by the NIC), the GSO is not executed, because is useless. After the execution of the GSO, the packets, that are passed to the device driver, are smaller (or equal) than MTU, so the TSO is unnecessary. For this reason the GSO doesn't look neither "ifp->if_hw_tsomax" nor hardware segment limits. The GSO is very useful when you can't use the TSO. Cheers, Stefano 2014-09-17 22:27 GMT+02:00 Hans Petter Selasky : > On 09/17/14 20:18, Stefano Garzarella wrote: > >> Hi Adrian, >> the results that I sent, regard just one flow, but I can try with two >> simultaneous flows and I'll send you the results. >> >> Thanks, >> Stefano >> >> > Hi Stefano, > > You might have seen the discussion about TSO. Is it so that the proposed > GSO feature only looks at the "ifp->if_hw_tsomax" field, and ignores > hardware limits regarding maximum segment size and maximum segment count? > > --HPS > -- *Stefano Garzarella* stefano.garzarella@gmail.com