From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ferruh Yigit Subject: Re: [PATCH v4 1/4] igb_uio: add wc option Date: Fri, 29 Jun 2018 14:20:36 +0100 Message-ID: <148bba87-27d5-9eac-6844-696e8f0d0a9a@intel.com> References: <1530267873-7236-2-git-send-email-rk@semihalf.com> <1530274637-10156-1-git-send-email-rk@semihalf.com> <1530274637-10156-2-git-send-email-rk@semihalf.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Cc: mw@semihalf.com, mk@semihalf.com, gtzalik@amazon.com, evgenys@amazon.com, matua@amazon.com, igorch@amazon.com, thomas@monjalon.net To: Rafal Kozik , dev@dpdk.org Return-path: Received: from mga02.intel.com (mga02.intel.com [134.134.136.20]) by dpdk.org (Postfix) with ESMTP id C1BDC1DB9 for ; Fri, 29 Jun 2018 15:20:40 +0200 (CEST) In-Reply-To: <1530274637-10156-2-git-send-email-rk@semihalf.com> Content-Language: en-US List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" On 6/29/2018 1:17 PM, Rafal Kozik wrote: > From: Kozik > > Write combining (WC) increases NIC performance by making better > utilization of PCI bus, but cannot be use by all PMD. > > To get internal_addr memory need to be mapped. But as memory could not be > mapped twice: with and without WC it should be skipped for WC. [1] > > To do not spoil other drivers that potentially could use internal_addr, > parameter wc_activate adds possibility to skip it for those PMDs, > that do not use it. > > [1] https://www.kernel.org/doc/ols/2008/ols2008v2-pages-135-144.pdf > section 5.3 and 5.4 > > Signed-off-by: Rafal Kozik > Acked-by: Bruce Richardson Acked-by: Ferruh Yigit (I am still not able to confirm this is needed, but since the behavior change is controlled by module param and internal_addr is not used at all, no need to block the patch)