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 CA50CC433FE for ; Wed, 9 Nov 2022 15:27:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232025AbiKIP1L (ORCPT ); Wed, 9 Nov 2022 10:27:11 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57404 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232097AbiKIP1H (ORCPT ); Wed, 9 Nov 2022 10:27:07 -0500 Received: from smtp8.emailarray.com (smtp8.emailarray.com [65.39.216.67]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 736E7D45 for ; Wed, 9 Nov 2022 07:27:02 -0800 (PST) Received: (qmail 57622 invoked by uid 89); 9 Nov 2022 15:27:01 -0000 Received: from unknown (HELO localhost) (amxlbW9uQGZsdWdzdmFtcC5jb21ANzEuMjEyLjEzMS44MA==) (POLARISLOCAL) by smtp8.emailarray.com with SMTP; 9 Nov 2022 15:27:01 -0000 Date: Wed, 9 Nov 2022 07:27:00 -0800 From: Jonathan Lemon To: Dust Li Cc: io-uring@vger.kernel.org, kernel-team@meta.com Subject: Re: [PATCH v1 00/15] zero-copy RX for io_uring Message-ID: <20221109152700.syfhhmkdloi5gmas@bsd-mbp.local> References: <20221108050521.3198458-1-jonathan.lemon@gmail.com> <20221109063742.GI56517@linux.alibaba.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221109063742.GI56517@linux.alibaba.com> Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On Wed, Nov 09, 2022 at 02:37:42PM +0800, Dust Li wrote: > > Haven't dive into your test case yet, but the performance data > looks disappointing > > I don't know why we need zerocopy if we can't get a big performance > gain. The cited numbers are intended to show that there is no network bandwidth performance drop from using RECV_ZC. For the systems under test (25Gb, 50Gb), we are getting linerate already, so there wouldn't be any BW improvement. The zerocopy gains come from a reduction in memory bandwith, removing the user memcpy overhead, reducing the CPU usage. This is why I put up the changes for iperf3, so cpu and membw usage metrics can be collected while under network load. > Have you tested large messages with jumbo or LRO enabled ? Haven't tested jumbo frames, but these are with GRO support. -- Jonathan