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 X-Spam-Level: X-Spam-Status: No, score=-1.7 required=3.0 tests=DATE_IN_PAST_96_XX, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id ED1C8C2D0F3 for ; Thu, 2 Apr 2020 14:48:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CDB0B2074D for ; Thu, 2 Apr 2020 14:48:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388704AbgDBOsh (ORCPT ); Thu, 2 Apr 2020 10:48:37 -0400 Received: from shards.monkeyblade.net ([23.128.96.9]:47676 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388288AbgDBOsh (ORCPT ); Thu, 2 Apr 2020 10:48:37 -0400 Received: from localhost (unknown [IPv6:2601:601:9f00:477::3d5]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) (Authenticated sender: davem-davemloft) by shards.monkeyblade.net (Postfix) with ESMTPSA id D9B9D128A8287; Thu, 2 Apr 2020 07:48:36 -0700 (PDT) Date: Wed, 25 Mar 2020 11:31:02 -0700 (PDT) Message-Id: <20200325.113102.661246567769402013.davem@davemloft.net> To: edumazet@google.com Cc: netdev@vger.kernel.org, eric.dumazet@gmail.com Subject: Re: [PATCH net-next] net: use indirect call wrappers for skb_copy_datagram_iter() From: David Miller In-Reply-To: <20200325022321.21944-1-edumazet@google.com> References: <20200325022321.21944-1-edumazet@google.com> X-Mailer: Mew version 6.8 on Emacs 26.1 Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.5.12 (shards.monkeyblade.net [149.20.54.216]); Thu, 02 Apr 2020 07:48:37 -0700 (PDT) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Eric Dumazet Date: Tue, 24 Mar 2020 19:23:21 -0700 > TCP recvmsg() calls skb_copy_datagram_iter(), which > calls an indirect function (cb pointing to simple_copy_to_iter()) > for every MSS (fragment) present in the skb. > > CONFIG_RETPOLINE=y forces a very expensive operation > that we can avoid thanks to indirect call wrappers. > > This patch gives a 13% increase of performance on > a single flow, if the bottleneck is the thread reading > the TCP socket. > > Signed-off-by: Eric Dumazet Applied, thanks Eric.