From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [ofa-general] Re: [PATCH RFC] RDMA/CMA: Allocate PS_TCPportsfrom the host TCP port space. Date: Sun, 19 Aug 2007 16:12:06 -0700 (PDT) Message-ID: <20070819.161206.94555994.davem@davemloft.net> References: <20070819.123212.13769462.davem@davemloft.net> <8A71B368A89016469F72CD08050AD334018E209C@maui.asicdesigners.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: jeff@garzik.org, netdev@vger.kernel.org, rdreier@cisco.com, linux-kernel@vger.kernel.org, general@lists.openfabrics.org To: andi@firstfloor.org Return-path: In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: general-bounces@lists.openfabrics.org Errors-To: general-bounces@lists.openfabrics.org List-Id: netdev.vger.kernel.org From: Andi Kleen Date: 20 Aug 2007 01:27:35 +0200 > "Felix Marti" writes: > > > what benefits does the TSO infrastructure give the > > non-TSO capable devices? > > It improves performance on software queueing devices between guests > and hypervisors. This is a more and more important application these > days. Even when the system running the Hypervisor has a non TSO > capable device in the end it'll still save CPU cycles this way. Right now > virtualized IO tends to much more CPU intensive than direct IO so any > help it can get is beneficial. > > It also makes loopback faster, although given that's probably not that > useful. > > And a lot of the "TSO infrastructure" was needed for zero copy TX anyways, > which benefits most reasonable modern NICs (anything with hardware > checksumming) And also, you can enable TSO generation for a non-TSO-hw device and get all of the segmentation overhead reduction gains which works out as a pure win as long as the device can at a minimum do checksumming.