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=-3.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 0A82AC46466 for ; Sat, 3 Oct 2020 02:06:51 +0000 (UTC) Received: from hemlock.osuosl.org (smtp2.osuosl.org [140.211.166.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 4BB642074B for ; Sat, 3 Oct 2020 02:06:50 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4BB642074B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=davemloft.net Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linux-kernel-mentees-bounces@lists.linuxfoundation.org Received: from localhost (localhost [127.0.0.1]) by hemlock.osuosl.org (Postfix) with ESMTP id D9AA186947; Sat, 3 Oct 2020 02:06:49 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from hemlock.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id TYd5hGCt-KZ6; Sat, 3 Oct 2020 02:06:47 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by hemlock.osuosl.org (Postfix) with ESMTP id DFEFF86DAC; Sat, 3 Oct 2020 02:06:47 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id B7372C0895; Sat, 3 Oct 2020 02:06:47 +0000 (UTC) Received: from hemlock.osuosl.org (smtp2.osuosl.org [140.211.166.133]) by lists.linuxfoundation.org (Postfix) with ESMTP id 3E0E8C0051 for ; Sat, 3 Oct 2020 02:06:46 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by hemlock.osuosl.org (Postfix) with ESMTP id 3A0B086947 for ; Sat, 3 Oct 2020 02:06:46 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from hemlock.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id e-G1M8RSUH1Y for ; Sat, 3 Oct 2020 02:06:43 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from shards.monkeyblade.net (shards.monkeyblade.net [23.128.96.9]) by hemlock.osuosl.org (Postfix) with ESMTPS id 80725868F7 for ; Sat, 3 Oct 2020 02:06:43 +0000 (UTC) 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 947C91260D092; Fri, 2 Oct 2020 18:49:53 -0700 (PDT) Date: Fri, 02 Oct 2020 19:06:38 -0700 (PDT) Message-Id: <20201002.190638.1090456279017490485.davem@davemloft.net> To: anant.thazhemadam@gmail.com From: David Miller In-Reply-To: <20200930051722.389587-1-anant.thazhemadam@gmail.com> References: <20200930051722.389587-1-anant.thazhemadam@gmail.com> X-Mailer: Mew version 6.8 on Emacs 27.1 Mime-Version: 1.0 X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.5.12 (shards.monkeyblade.net [2620:137:e000::1:9]); Fri, 02 Oct 2020 18:49:54 -0700 (PDT) Cc: hawk@kernel.org, daniel@iogearbox.net, mst@redhat.com, netdev@vger.kernel.org, jasowang@redhat.com, john.fastabend@gmail.com, ast@kernel.org, virtualization@lists.linux-foundation.org, kuba@kernel.org, bpf@vger.kernel.org, linux-kernel-mentees@lists.linuxfoundation.org, linux-kernel@vger.kernel.org Subject: Re: [Linux-kernel-mentees] [PATCH 0/2] reorder members of structures in virtio_net for optimization X-BeenThere: linux-kernel-mentees@lists.linuxfoundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-kernel-mentees-bounces@lists.linuxfoundation.org Sender: "Linux-kernel-mentees" From: Anant Thazhemadam Date: Wed, 30 Sep 2020 10:47:20 +0530 > The structures virtnet_info and receive_queue have byte holes in > middle, and their members could do with some rearranging > (order-of-declaration wise) in order to overcome this. > > Rearranging the members helps in: > * elimination the byte holes in the middle of the structures > * reduce the size of the structure (virtnet_info) > * have more members stored in one cache line (as opposed to > unnecessarily crossing the cacheline boundary and spanning > different cachelines) > > The analysis was performed using pahole. > > These patches may be applied in any order. What effects do these changes have on performance? The cache locality for various TX and RX paths could be effected. I'm not applying these patches without some data on the performance impact. Thank you. _______________________________________________ Linux-kernel-mentees mailing list Linux-kernel-mentees@lists.linuxfoundation.org https://lists.linuxfoundation.org/mailman/listinfo/linux-kernel-mentees