From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga14.intel.com (mga14.intel.com [192.55.52.115]) by dpdk.org (Postfix) with ESMTP id E93125A62 for ; Fri, 27 Mar 2015 13:21:59 +0100 (CET) Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by fmsmga103.fm.intel.com with ESMTP; 27 Mar 2015 05:21:59 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.11,478,1422950400"; d="scan'208";a="473497417" Received: from irvmail001.ir.intel.com ([163.33.26.43]) by FMSMGA003.fm.intel.com with ESMTP; 27 Mar 2015 05:21:58 -0700 Received: from sivswdev02.ir.intel.com (sivswdev02.ir.intel.com [10.237.217.46]) by irvmail001.ir.intel.com (8.14.3/8.13.6/MailSET/Hub) with ESMTP id t2RCLv1L001081; Fri, 27 Mar 2015 12:21:57 GMT Received: from sivswdev02.ir.intel.com (localhost [127.0.0.1]) by sivswdev02.ir.intel.com with ESMTP id t2RCLuXm018683; Fri, 27 Mar 2015 12:21:56 GMT Received: (from jmcnam2x@localhost) by sivswdev02.ir.intel.com with id t2RCLur2018679; Fri, 27 Mar 2015 12:21:56 GMT From: John McNamara To: dev@dpdk.org Date: Fri, 27 Mar 2015 12:21:43 +0000 Message-Id: <1427458903-18639-2-git-send-email-john.mcnamara@intel.com> X-Mailer: git-send-email 1.7.4.1 In-Reply-To: <1427458903-18639-1-git-send-email-john.mcnamara@intel.com> References: <1425286674-17495-1-git-send-email-changchun.ouyang@intel.com> <1427458903-18639-1-git-send-email-john.mcnamara@intel.com> Subject: [dpdk-dev] [PATCH v3] doc: Update doc for vhost sample 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: , X-List-Received-Date: Fri, 27 Mar 2015 12:22:00 -0000 From: Ouyang Changchun Add some documentation updates for vhost sample app. Signed-off-by: Changchun Ouyang Signed-off-by: John McNamara --- doc/guides/sample_app_ug/vhost.rst | 55 ++++++++++++++++++++++++++++++++------ 1 file changed, 47 insertions(+), 8 deletions(-) diff --git a/doc/guides/sample_app_ug/vhost.rst b/doc/guides/sample_app_ug/vhost.rst index 4a6d434..7254578 100644 --- a/doc/guides/sample_app_ug/vhost.rst +++ b/doc/guides/sample_app_ug/vhost.rst @@ -1,3 +1,4 @@ + .. BSD LICENSE Copyright(c) 2010-2014 Intel Corporation. All rights reserved. All rights reserved. @@ -640,19 +641,57 @@ To call the QEMU wrapper automatically from libvirt, the following configuration Common Issues ~~~~~~~~~~~~~ -**QEMU failing to allocate memory on hugetlbfs.** +* QEMU failing to allocate memory on hugetlbfs:: -file_ram_alloc: can't mmap RAM pages: Cannot allocate memory + file_ram_alloc: can't mmap RAM pages: Cannot allocate memory -When running QEMU the above error implies that it has failed to allocate memory for the Virtual Machine on the hugetlbfs. -This is typically due to insufficient hugepages being free to support the allocation request. -The number of free hugepages can be checked as follows: + When running QEMU the above error implies that it has failed to allocate memory for the Virtual Machine on + the hugetlbfs. This is typically due to insufficient hugepages being free to support the allocation request. + The number of free hugepages can be checked as follows: -.. code-block:: console + .. code-block:: console + + user@target:cat /sys/kernel/mm/hugepages/hugepages- / nr_hugepages + + The command above indicates how many hugepages are free to support QEMU's allocation request. + +* User space VHOST work properly with the guest with 2M sized hug pages: + + The guest may have 2M or 1G sized huge pages file, the user space VHOST can work properly in both cases. + +* User space VHOST will not work with QEMU without '-mem-prealloc' option: + + The current implementation work properly only when the guest memory is pre-allocated, so it is required to + use the correct QEMU version(e.g. 1.6) which supports '-mem-prealloc'; The option '-mem-prealloc' must be + specified explicitly in QEMU command line. + +* User space VHOST will not work with QEMU version without shared memory mapping: + + As shared memory mapping is mandatory for user space VHOST to work properly with the guest as user space VHOST + needs access the shared memory from the guest to receive and transmit packets. It is important to make sure + the QEMU version used supports shared memory mapping. + +* Using libvirt "virsh create" the qemu-wrap.py spawns a new process to run "qemu-kvm". This impacts the behavior + of the "virsh destroy" which kills the process running "qemu-wrap.py" without actually destroying the VM (leaves + the "qemu-kvm" process running): + + This following patch can fix this issue: + http://dpdk.org/ml/archives/dev/2014-June/003607.html + +* In Ubuntu environment, QEMU fail to start a new guest normally with user space VHOST due to hug pages can't be + allocated for the new guest.* + + The solution for this issue could be adding "-boot c" into QEMU command line to make sure the huge pages are + allocated properly and then the guest will startup normally. + + Use "cat /proc/meminfo" to check if there is any change in value of HugePages_Total and HugePages_Free after the + guest startup. - user@target:cat /sys/kernel/mm/hugepages/hugepages- / nr_hugepages +* Logging message: "eventfd_link: module verification failed: signature and/or required key missing - tainting kernel"* -The command above indicates how many hugepages are free to support QEMU's allocation request. + Ignore the above logging message. The message occurs due to the new module eventfd_link, which is not a standard + module of Linux, but it is necessary for user space VHOST current implementation(CUSE-based) to communicate with + the guest. Running DPDK in the Virtual Machine ----------------------------------- -- 1.8.1.4