From patchwork Sun Mar 22 18:09:58 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Jayakumar, Muthurajan" X-Patchwork-Id: 4102 Return-Path: X-Original-To: patchwork@dpdk.org Delivered-To: patchwork@dpdk.org Received: from [92.243.14.124] (localhost [IPv6:::1]) by dpdk.org (Postfix) with ESMTP id A9B955A50; Sun, 22 Mar 2015 19:10:02 +0100 (CET) Received: from mga01.intel.com (mga01.intel.com [192.55.52.88]) by dpdk.org (Postfix) with ESMTP id AA25B5A4F for ; Sun, 22 Mar 2015 19:10:00 +0100 (CET) Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by fmsmga101.fm.intel.com with ESMTP; 22 Mar 2015 11:09:59 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.11,447,1422950400"; d="scan'208";a="683925732" Received: from orsmsx105.amr.corp.intel.com ([10.22.225.132]) by fmsmga001.fm.intel.com with ESMTP; 22 Mar 2015 11:09:59 -0700 Received: from orsmsx153.amr.corp.intel.com (10.22.226.247) by ORSMSX105.amr.corp.intel.com (10.22.225.132) with Microsoft SMTP Server (TLS) id 14.3.195.1; Sun, 22 Mar 2015 11:09:59 -0700 Received: from orsmsx112.amr.corp.intel.com ([169.254.12.60]) by ORSMSX153.amr.corp.intel.com ([169.254.12.31]) with mapi id 14.03.0195.001; Sun, 22 Mar 2015 11:09:59 -0700 From: "Jayakumar, Muthurajan" To: "Butler, Siobhan A" , "dev@dpdk.org" Thread-Topic: [dpdk-dev] [PATCH] doc: added to faq section of release notes Thread-Index: AQHQZKOxIer+XZavJE+Xl+U7+ZKtkp0ozVsw Date: Sun, 22 Mar 2015 18:09:58 +0000 Message-ID: <5D695A7F6F10504DBD9B9187395A21797D1F2611@ORSMSX112.amr.corp.intel.com> References: <1427030707-6091-1-git-send-email-siobhan.a.butler@intel.com> In-Reply-To: <1427030707-6091-1-git-send-email-siobhan.a.butler@intel.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.22.254.138] MIME-Version: 1.0 Subject: Re: [dpdk-dev] [PATCH] doc: added to faq section of release notes X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" This is very useful. Thank you very much Siobhan. Thanks M Jay -----Original Message----- From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Siobhan Butler Sent: Sunday, March 22, 2015 6:25 AM To: dev@dpdk.org Subject: [dpdk-dev] [PATCH] doc: added to faq section of release notes Added some of the questions posted to the mailing list to the FAQ section of release notes. Signed-off-by: Siobhan Butler --- doc/guides/rel_notes/faq.rst | 35 +++++++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+) 1.8.3.1 diff --git a/doc/guides/rel_notes/faq.rst b/doc/guides/rel_notes/faq.rst index 054db10..14b1167 100644 --- a/doc/guides/rel_notes/faq.rst +++ b/doc/guides/rel_notes/faq.rst @@ -191,3 +191,38 @@ In this case, this has to be done manually on the VM host, using the following c where being the interface providing the virtual functions for example, eth0, being the virtual function number, for example 0, and being the desired MAC address. + +Is it safe to add an entry to the hash table while running? +------------------------------------------------------------ +Currently the table implementation is not a thread safe implementation and assumes that locking between threads and processes is handled by the user's application. +This is likely to be supported in future releases. + +What is the purpose of setting iommu=pt? +---------------------------------------- +DPDK uses a 1:1 mapping and does not support IOMMU. IOMMU allows for simpler VM physical address translation. +The second role of IOMMU is to allow protection from unwanted memory access by an unsafe device that has DMA privileges. +Unfortunately, the protection comes with an extremely high perfomance cost for high speed NICs. + +iommu=pt disables IOMMU support for the hypervisor. + +When trying to send packets from an application to itself, meaning smac==dmac, using Intel(R) 82599 VF packets are lost. +----------------------------------------------------------------------- +------------------------------------------------- +Check on register LLE(PFVMTXSSW[n]), which allows an individual pool to send traffic and have it looped back to itself. + +Can I split packet RX to use DPDK and have an application's higher order functions continue using Linux* pthread? +----------------------------------------------------------------------- +------------------------------------------ +The DPDK's lcore threads are Linux* pthreads bound onto specific cores. +Configure the DPDK to do work on the same cores and run the +application's other work on other cores using the DPDK's "coremask" setting to specify which cores it should launch itself on. + +Is it possible to exchange data between DPDK processes and regular userspace processes via some shared memory or IPC mechanism? +----------------------------------------------------------------------- +-------------------------------------------------------- +Yes - DPDK processes are regular Linux/BSD processes, and can use all OS provided IPC mechanisms. + +Can the multiple queues in Intel(R) I350 be used with DPDK? +----------------------------------------------------------- +I350 has RSS support and 8 queue pairs can be used in RSS mode. It should work with multi-queue DPDK applications using RSS. + +How can hugepage-backed memory be shared among multiple processes? +------------------------------------------------------------------ +See the Primary and Secondary examples in the multi-process sample application. --