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=-4.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS autolearn=ham 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 19BC7C282C3 for ; Tue, 22 Jan 2019 22:52:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DC128217D6 for ; Tue, 22 Jan 2019 22:52:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726863AbfAVWw0 (ORCPT ); Tue, 22 Jan 2019 17:52:26 -0500 Received: from shards.monkeyblade.net ([23.128.96.9]:37344 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726175AbfAVWw0 (ORCPT ); Tue, 22 Jan 2019 17:52:26 -0500 Received: from localhost (unknown [IPv6:2601:601:9f80:35cd::bf5]) (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 EE99A14D46A48; Tue, 22 Jan 2019 14:52:25 -0800 (PST) Date: Tue, 22 Jan 2019 14:52:25 -0800 (PST) Message-Id: <20190122.145225.1783445146286517629.davem@davemloft.net> To: hkallweit1@gmail.com Cc: nic_swsd@realtek.com, netdev@vger.kernel.org, edumazet@google.com Subject: Re: [PATCH net-next] r8169: improve rx buffer allocation From: David Miller In-Reply-To: References: 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]); Tue, 22 Jan 2019 14:52:26 -0800 (PST) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Heiner Kallweit Date: Sun, 20 Jan 2019 11:12:01 +0100 > 8 years ago, as part of 6f0333b8fde4 ("r8169: use 50% less ram for RX > ring"), the alignment requirement for rx buffers was silently changed > from 8 bytes to 16 bytes. I found nothing explaining this, also the > chip specs I have only mention an 8 byte requirement. > AFAICS kmalloc_node() guarantees allocated memory to be at least > "long long" aligned, what is 8 bytes on a 32 bit machine. > So we can take this memory as-is and avoid some overhead by changing > the alignment requirement back to 8 bytes. > > Signed-off-by: Heiner Kallweit Applied. It might have been for cache line alignment or something silly like that. But totally undocumented.