From mboxrd@z Thu Jan 1 00:00:00 1970 From: Aaron Conole Subject: Re: [PATCH v6 01/12] eal/pci: introduce PCI driver iova as va flag Date: Thu, 17 Aug 2017 08:35:06 -0400 Message-ID: References: <20170724084004.25542-1-santosh.shukla@caviumnetworks.com> <20170814161059.6684-1-santosh.shukla@caviumnetworks.com> <20170814161059.6684-2-santosh.shukla@caviumnetworks.com> Mime-Version: 1.0 Content-Type: text/plain Cc: dev@dpdk.org, olivier.matz@6wind.com, thomas@monjalon.net, jerin.jacob@caviumnetworks.com, hemant.agrawal@nxp.com, maxime.coquelin@redhat.com, sergio.gonzalez.monroy@intel.com, bruce.richardson@intel.com, shreyansh.jain@nxp.com, gaetan.rivet@6wind.com, anatoly.burakov@intel.com, stephen@networkplumber.org To: Santosh Shukla Return-path: Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) by dpdk.org (Postfix) with ESMTP id E7CC0917F for ; Thu, 17 Aug 2017 14:35:12 +0200 (CEST) In-Reply-To: <20170814161059.6684-2-santosh.shukla@caviumnetworks.com> (Santosh Shukla's message of "Mon, 14 Aug 2017 21:40:48 +0530") List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" Santosh Shukla writes: > Introducing RTE_PCI_DRV_IOVA_AS_VA flag. Flag used when driver needs > to operate in iova=va mode. > > Why driver need iova=va mapping? > > On NPU style co-processors like Octeontx, the buffer recycling has been > done in HW, unlike SW model. Here is the data flow: > 1) On control path, Fill the HW mempool with buffers(iova as pa address) > 2) on rx_burst, HW gives you IOVA address(iova as pa address) > 3) As application expects VA to operate on it, rx_burst() needs to > convert to _va from _pa. Which is very expensive. > Instead of that if iova as va mapping, we can avoid the cost of > converting with help of IOMMU/SMMU. > > Signed-off-by: Santosh Shukla > Signed-off-by: Jerin Jacob > Reviewed-by: Maxime Coquelin > --- This should be folded into patch 5; there's no clear need for it until then.