From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B383FC433F5 for ; Thu, 10 Feb 2022 14:04:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241098AbiBJOEd (ORCPT ); Thu, 10 Feb 2022 09:04:33 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:57308 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240156AbiBJOEc (ORCPT ); Thu, 10 Feb 2022 09:04:32 -0500 Received: from out1.migadu.com (out1.migadu.com [IPv6:2001:41d0:2:863f::]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 733F81B3 for ; Thu, 10 Feb 2022 06:04:33 -0800 (PST) Message-ID: <11e71fc4-6194-9290-df0e-f062af91cc8c@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1644501871; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=5z+lqkTF72U/0bw9QC9m1+PIzuMmVNJJmeFI04X6K+U=; b=TBplsLEyKWW4fjJ0xCnds3IKZlSWio6vzfvvESpm9WjJjs6G3tUGmGgW90+ZkcGUFEl47e rYcvdhp/sgoF3v2vqmFE7zoiYgLKjR3yf/qQaTa1ePQKTvpZZ3NSKisIxY5aYDwZyq6upH qfGmcpXiVqngdsHahHGevcpdB1krMho= Date: Thu, 10 Feb 2022 22:04:22 +0800 MIME-Version: 1.0 Subject: Re: Soft-RoCE performance To: "Pearson, Robert B" , Christian Blume , RDMA mailing list References: X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Yanjun Zhu In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Migadu-Auth-User: linux.dev Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org 在 2022/2/10 13:13, Pearson, Robert B 写道: > Christian, > > There are two key differences between TCP and soft RoCE. Most importantly TCP can use a 64KiB MTU which is fragmented by TSO or GSO if your NIC doesn't support TSO while soft RoCE is limited by the protocol to a 4KiB payload. With overhead for headers you need a link MTU of about 4096+256. If your application is going between soft RoCE and hard RoCE you have to live with this limit and compute ICRC on each packet. Checking is optional since RoCE packets have a crc32 checksum from ethernet. If you are using soft RoCE to soft RoCE you can ignore both ICRC calculations and with a patch increase the MTU above 4KiB. I have measured write performance up to around 35 GB/s Thanks, I have also reached the big bandwidth with the same methods. How about latency of soft roce? Zhu Yanjun in local loopback on a single 12 core box (AMD 3900x) using 12 IO threads, 16KB MTU, and ICRC disabled for 1MB messages. This is on head of tree with some patches not yet upstream. > > Bob Pearson > rpearsonhpe@gmail.com > rpearson@hpe.com > > > -----Original Message----- > From: Christian Blume > Sent: Wednesday, February 9, 2022 9:34 PM > To: RDMA mailing list > Subject: Soft-RoCE performance > > Hello! > > I am seeing that Soft-RoCE has much lower throughput than TCP. Is that expected? If not, are there typical config parameters I can fiddle with? > > When running iperf I am getting around 300MB/s whereas it's only around 100MB/s using ib_write_bw from perftests. > > This is between two machines running Ubuntu20.04 with the 5.11 kernel. > > Cheers, > Christian