From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH net-next 3/3] mlx4_en: Saving mem access on data path Date: Thu, 23 Feb 2012 14:47:49 -0500 (EST) Message-ID: <20120223.144749.1718133820851859801.davem@davemloft.net> References: <4F464074.9050901@mellanox.co.il> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org To: yevgenyp@mellanox.co.il Return-path: Received: from shards.monkeyblade.net ([198.137.202.13]:55726 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755942Ab2BWTrz (ORCPT ); Thu, 23 Feb 2012 14:47:55 -0500 In-Reply-To: <4F464074.9050901@mellanox.co.il> Sender: netdev-owner@vger.kernel.org List-ID: From: Yevgeny Petrilin Date: Thu, 23 Feb 2012 15:34:44 +0200 > > Localized the pdev->dev, and using dma_map instead of pci_map > There are multiple map/unmap operations on data path, > optimizing those by saving redundant pointer access. > > Signed-off-by: Yevgeny Petrilin I doubt you can measure any improvement from this at all, all of the real cost is going to be in programming the hardware (both the networking chip and potentially any IOMMU hardware to setup the DMA mappings). A pointer deref in of your datastructures will be unnoticable. When you make changes like this I want you to justify them with real data and facts. I think this entire patch set was in very poor taste and judgment.