From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: [PATCH] mlx4_en: map entire pages to increase throughput Date: Tue, 17 Jul 2012 15:50:59 +0200 Message-ID: <1342533059.2626.661.camel@edumazet-glaptop> References: <50044F1D.6000703@hp.com> <20120716.222903.367603216293954363.davem@davemloft.net> <20120717.055005.1912765690890797652.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: David.Laight@ACULAB.COM, rick.jones2@hp.com, cascardo@linux.vnet.ibm.com, netdev@vger.kernel.org, yevgenyp@mellanox.co.il, ogerlitz@mellanox.com, amirv@mellanox.com, brking@linux.vnet.ibm.com, leitao@linux.vnet.ibm.com, klebers@linux.vnet.ibm.com To: David Miller Return-path: Received: from mail-ee0-f46.google.com ([74.125.83.46]:43738 "EHLO mail-ee0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752359Ab2GQNvH (ORCPT ); Tue, 17 Jul 2012 09:51:07 -0400 Received: by eekc13 with SMTP id c13so165896eek.19 for ; Tue, 17 Jul 2012 06:51:05 -0700 (PDT) In-Reply-To: <20120717.055005.1912765690890797652.davem@davemloft.net> Sender: netdev-owner@vger.kernel.org List-ID: On Tue, 2012-07-17 at 05:50 -0700, David Miller wrote: > From: "David Laight" > Date: Tue, 17 Jul 2012 13:42:04 +0100 > > > Would there be any mileage in permanently allocating IOMMU > > virtual address to the ring entries, then 'just' assigning > > the correct physical address during rx/tx setup? > > There is a not a one to one mapping between these two entities, > in particular on the transmit side. > > A transmit packet can have multiple segments, some of which are > larger than one IOMMU page. And on rx side, permanently allocating IOMMU would need to copy all incoming frames to newly allocated memory. Annot this IOMMU performance problem can be solved on its side, instead of having to shuffle things in all drivers ?