From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michal Krawczyk Subject: [PATCH 5/5] doc: add instructions for enabling WC in ENAv2 PMD Date: Fri, 25 Jan 2019 09:10:28 +0100 Message-ID: <1548403828-31870-6-git-send-email-mk@semihalf.com> References: <1548403828-31870-1-git-send-email-mk@semihalf.com> Cc: rk@semihalf.com, dev@dpdk.org To: gtzalik@amazon.com, mw@semihalf.com, matua@amazon.com Return-path: Received: from mail-lj1-f193.google.com (mail-lj1-f193.google.com [209.85.208.193]) by dpdk.org (Postfix) with ESMTP id 88998316B for ; Fri, 25 Jan 2019 09:10:38 +0100 (CET) Received: by mail-lj1-f193.google.com with SMTP id v1-v6so7643522ljd.0 for ; Fri, 25 Jan 2019 00:10:38 -0800 (PST) In-Reply-To: <1548403828-31870-1-git-send-email-mk@semihalf.com> List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" From: Rafal Kozik ENAv2 hardware provides Low Latency Queue v2 (LLQv2). It needs kernel PCI driver to support write combining (WC). This patch add information how to use it with igb_uio and vfio-pci drivers. Signed-off-by: Rafal Kozik Acked-by: Michal Krawczyk --- doc/guides/nics/ena.rst | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-) diff --git a/doc/guides/nics/ena.rst b/doc/guides/nics/ena.rst index 9f0a650..80da4b6 100644 --- a/doc/guides/nics/ena.rst +++ b/doc/guides/nics/ena.rst @@ -183,10 +183,22 @@ Prerequisites #. Prepare the system as recommended by DPDK suite. This includes environment variables, hugepages configuration, tool-chains and configuration. -#. ENA PMD can operate with ``vfio-pci`` or ``igb_uio`` driver. +#. ENA PMD can operate with ``vfio-pci``(*) or ``igb_uio`` driver. + + (*) ENAv2 hardware supports Low Latency Queue v2 (LLQv2). This feature + reduces the latency of the packets by pushing the header directly through + the PCI to the device, before the DMA is even triggered. For proper work + kernel PCI driver must support write combining (WC). In mainline version of + ``igb_uio`` (in DPDK repo) it must be enabled by loding module with + ``wc_activate=1`` flag (example below). However, mainline's vfio-pci + driver in kernel doesn't have WC support yet (planed to be added). + If vfio-pci used user should be either turn off ENAv2 (to avoid performance + impact) or recompile vfio-pci driver with patch provided in + `amzn-github `_. #. Insert ``vfio-pci`` or ``igb_uio`` kernel module using the command - ``modprobe vfio-pci`` or ``modprobe igb_uio`` respectively. + ``modprobe vfio-pci`` or ``modprobe uio; insmod igb_uio.ko wc_activate=1`` + respectively. #. For ``vfio-pci`` users only: Please make sure that ``IOMMU`` is enabled in your system, -- 2.7.4