From: Huawei Xie Date: Wed, 11 Mar 2015 16:21:47 +0000 (+0800) Subject: doc: add vhost-user to sample guide X-Git-Tag: spdx-start~9351 X-Git-Url: http://git.droids-corp.org/?a=commitdiff_plain;h=9bc23cb8209cd527e8f8aefac0a9b240411749d0;p=dpdk.git doc: add vhost-user to sample guide add vhost user documentation fix some minor issues Signed-off-by: Huawei Xie --- diff --git a/doc/guides/sample_app_ug/vhost.rst b/doc/guides/sample_app_ug/vhost.rst index 25d91bbda6..d542929db0 100644 --- a/doc/guides/sample_app_ug/vhost.rst +++ b/doc/guides/sample_app_ug/vhost.rst @@ -45,7 +45,7 @@ Background Virtio networking (virtio-net) was developed as the Linux* KVM para-virtualized method for communicating network packets between host and guest. It was found that virtio-net performance was poor due to context switching and packet copying between host, guest, and QEMU. -The following figure shows the system architecture for a virtio- based networking (virtio-net). +The following figure shows the system architecture for a virtio-based networking (virtio-net). .. _figure_16: @@ -89,20 +89,34 @@ Sample Code Overview The DPDK vhost-net sample code demonstrates KVM (QEMU) offloading the servicing of a Virtual Machine's (VM's) virtio-net devices to a DPDK-based application in place of the kernel's vhost-net module. -The DPDK vhost-net sample code is a simple packet switching application with the following features: +The DPDK vhost-net sample code is based on vhost library. Vhost library is developed for user space ethernet switch to +easily integrate with vhost functionality. + +The vhost library implements the following features: * Management of virtio-net device creation/destruction events. -* Mapping of the VM's physical memory into the DPDK vhost-net sample code's address space. +* Mapping of the VM's physical memory into the DPDK vhost-net's address space. * Triggering/receiving notifications to/from VMs via eventfds. * A virtio-net back-end implementation providing a subset of virtio-net features. +There are two vhost implementations in vhost library, vhost cuse and vhost user. In vhost cuse, a character device driver is implemented to +receive and process vhost requests through ioctl messages. In vhost user, a socket server is created to received vhost requests through +socket messages. Most of the messages share the same handler routine. + +.. note:: + **Any vhost cuse specific requirement in the following sections will be emphasized**. + +Two impelmentations are turned on and off statically through configure file. Only one implementation could be turned on. They don't co-exist in current implementation. + +The vhost sample code application is a simple packet switching application with the following feature: + * Packet switching between virtio-net devices and the network interface card, including using VMDQs to reduce the switching that needs to be performed in software. -The following figure shows the architecture of the Vhost sample application. +The following figure shows the architecture of the Vhost sample application based on vhost-cuse. .. _figure_18: @@ -131,15 +145,19 @@ The example in this section have been validated with the following distributions * Fedora* 19 +* Fedora* 20 + Prerequisites ------------- This section lists prerequisite packages that must be installed. -Installing Packages on the Host -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +Installing Packages on the Host(vhost cuse required) +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -The vhost sample code uses the following packages; fuse, fuse-devel, and kernel- modules-extra. +The vhost cuse code uses the following packages; fuse, fuse-devel, and kernel-modules-extra. +The vhost user code don't rely on those modules as eventfds are already installed into vhost process through +unix domain socket. #. Install Fuse Development Libraries and headers: @@ -153,6 +171,11 @@ The vhost sample code uses the following packages; fuse, fuse-devel, and kernel- yum -y install kernel-modules-extra +QEMU simulator +~~~~~~~~~~~~~~ + +For vhost user, qemu 2.2 is required. + Setting up the Execution Environment ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ @@ -202,7 +225,7 @@ In this section, we create a second hugetlbs mount point to allocate hugepages f .. code-block:: console - echo 256 > /sys/kernel/mm/hugepages/hugepages-2048kB/ nr_hugepages + echo 256 > /sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages #. Mount hugetlbs at a separate mount point for 2 MB pages: @@ -251,6 +274,8 @@ at the command line as follows. Observe that in the example, "-device" and "-netdev" are repeated for two virtio-net devices. +For vhost cuse: + .. code-block:: console user@target:~$ qemu-system-x86_64 ... \ @@ -259,15 +284,46 @@ at the command line as follows. -netdev tap,id=hostnet2,vhost=on,vhostfd= \ -device virtio-net-pci, netdev=hostnet2,id=net1 +For vhost user: + +.. code-block:: console + + user@target:~$ qemu-system-x86_64 ... \ + -chardev socket,id=char1,path= \ + -netdev type=vhost-user,id=hostnet1,chardev=char1 \ + -device virtio-net-pci,netdev=hostnet1,id=net1 \ + -chardev socket,id=char2,path= \ + -netdev type=vhost-user,id=hostnet2,chardev=char2 \ + -device virtio-net-pci,netdev=hostnet2,id=net2 + +sock_path is the path for the socket file created by vhost. Compiling the Sample Code ------------------------- +#. Compile vhost lib: + + To enable vhost, turn on vhost library in the configure file config/common_linuxapp. + + .. code-block:: console + + CONFIG_RTE_LIBRTE_VHOST=n + + vhost user is turned on by default in the lib/librte_vhost/Makefile. + To enable vhost cuse, uncomment vhost cuse and comment vhost user manually. In future, a configure will be created for switch between two implementations. + + .. code-block:: console + + SRCS-$(CONFIG_RTE_LIBRTE_VHOST) += vhost_cuse/vhost-net-cdev.c vhost_cuse/virtio-net-cdev.c vhost_cuse/eventfd_copy.c + #SRCS-$(CONFIG_RTE_LIBRTE_VHOST) += vhost_user/vhost-net-user.c vhost_user/virtio-net-user.c vhost_user/fd_man.c + + After vhost is enabled and the implementation is selected, build the vhost library. #. Go to the examples directory: .. code-block:: console - export RTE_SDK=/path/to/rte_sdk cd ${RTE_SDK}/examples/vhost-net + export RTE_SDK=/path/to/rte_sdk + cd ${RTE_SDK}/examples/vhost #. Set the target (a default target is used if not specified). For example: @@ -309,13 +365,13 @@ Compiling the Sample Code cd ${RTE_SDK}/examples/vhost make -#. Go to the eventfd_link directory: +#. Go to the eventfd_link directory(vhost cuse required): .. code-block:: console - cd ${RTE_SDK}/examples/vhost-net/eventfd_link + cd ${RTE_SDK}/lib/librte_vhost/eventfd_link -#. Build the eventfd_link kernel module: +#. Build the eventfd_link kernel module(vhost cuse required): .. code-block:: console @@ -324,20 +380,20 @@ Compiling the Sample Code Running the Sample Code ----------------------- -#. Install the cuse kernel module: +#. Install the cuse kernel module(vhost cuse required): .. code-block:: console modprobe cuse -#. Go to the eventfd_link directory: +#. Go to the eventfd_link directory(vhost cuse required): .. code-block:: console export RTE_SDK=/path/to/rte_sdk - cd ${RTE_SDK}/examples/vhost-net/eventfd_link + cd ${RTE_SDK}/lib/librte_vhost/eventfd_link -#. Install the eventfd_link module: +#. Install the eventfd_link module(vhost cuse required): .. code-block:: console @@ -348,14 +404,22 @@ Running the Sample Code .. code-block:: console export RTE_SDK=/path/to/rte_sdk - cd ${RTE_SDK}/examples/vhost-net + cd ${RTE_SDK}/examples/vhost #. Run the vhost-switch sample code: + vhost cuse: + .. code-block:: console user@target:~$ ./build/app/vhost-switch -c f -n 4 --huge-dir / mnt/huge -- -p 0x1 --dev-basename usvhost --dev-index 1 + vhost user: a socket file named usvhost will be created under current directory. Use its path as the socket path in guest's qemu commandline. + + .. code-block:: console + + user@target:~$ ./build/app/vhost-switch -c f -n 4 --huge-dir / mnt/huge -- -p 0x1 --dev-basename usvhost + .. note:: Please note the huge-dir parameter instructs the DPDK to allocate its memory from the 2 MB page hugetlbfs. @@ -364,7 +428,7 @@ Parameters ~~~~~~~~~~ **Basename and Index.** -The DPDK vhost-net sample code uses a Linux* character device to communicate with QEMU. +vhost cuse uses a Linux* character device to communicate with QEMU. The basename and the index are used to generate the character devices name. /dev/- @@ -485,15 +549,15 @@ QEMU must be executed with specific parameters to: .. code-block:: console - user@target:~$ qemu-system-x86_64 ... -device virtio-net-pci, netdev=hostnet1,id=net1 ... + user@target:~$ qemu-system-x86_64 ... -device virtio-net-pci,netdev=hostnet1,id=net1 ... * Ensure the guest's virtio-net network adapter is configured with offloads disabled. .. code-block:: console - user@target:~$ qemu-system-x86_64 ... -device virtio-net-pci, netdev=hostnet1,id=net1,csum=off,gso=off,guest_tso4=off,guest_ tso6=off,guest_ecn=off + user@target:~$ qemu-system-x86_64 ... -device virtio-net-pci,netdev=hostnet1,id=net1,csum=off,gso=off,guest_tso4=off,guest_tso6=off,guest_ecn=off -* Redirect QEMU to communicate with the DPDK vhost-net sample code in place of the vhost-net kernel module. +* Redirect QEMU to communicate with the DPDK vhost-net sample code in place of the vhost-net kernel module(vhost cuse). .. code-block:: console @@ -510,8 +574,8 @@ QEMU must be executed with specific parameters to: The QEMU wrapper (qemu-wrap.py) is a Python script designed to automate the QEMU configuration described above. It also facilitates integration with libvirt, although the script may also be used standalone without libvirt. -Redirecting QEMU to vhost-net Sample Code -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +Redirecting QEMU to vhost-net Sample Code(vhost cuse) +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ To redirect QEMU to the vhost-net sample code implementation of the vhost-net API, an open file descriptor must be passed to QEMU running as a child process. @@ -524,7 +588,7 @@ an open file descriptor must be passed to QEMU running as a child process. .. note:: - This process is automated in the QEMU wrapper script discussed in Section 22.7.3. + This process is automated in the QEMU wrapper script discussed in Section 24.7.3. Mapping the Virtual Machine's Memory ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ @@ -541,7 +605,8 @@ In this case, the path passed to the guest should be that of the 1 GB page huget .. note:: - This process is automated in the QEMU wrapper script discussed in Section 22.7.3. + This process is automated in the QEMU wrapper script discussed in Section 24.7.3. + The following two sections only applies to vhost cuse. For vhost-user, please make corresponding changes to qemu-wrapper script and guest XML file. QEMU Wrapper Script ~~~~~~~~~~~~~~~~~~~ @@ -570,8 +635,8 @@ which will become the following call to QEMU: .. code-block:: console /usr/local/bin/qemu-system-x86_64 -machine pc-i440fx-1.4,accel=kvm,usb=off -cpu SandyBridge -smp 4,sockets=4,cores=1,threads=1 - -netdev tap,id=hostnet1,vhost=on,vhostfd= -device virtio-net- pci,netdev=hostnet1,id=net1, - csum=off,gso=off,guest_tso4=off,gu est_tso6=off,guest_ecn=off -hda -m 4096 -mem-path /dev/hugepages -mem-prealloc + -netdev tap,id=hostnet1,vhost=on,vhostfd= -device virtio-net-pci,netdev=hostnet1,id=net1, + csum=off,gso=off,guest_tso4=off,guest_tso6=off,guest_ecn=off -hda -m 4096 -mem-path /dev/hugepages -mem-prealloc Libvirt Integration ~~~~~~~~~~~~~~~~~~~ @@ -638,7 +703,7 @@ To call the QEMU wrapper automatically from libvirt, the following configuration emul_path = "/usr/local/bin/qemu-system-x86_64" - * Configure the "us_vhost_path" variable to point to the DPDK vhost- net sample code's character devices name. + * Configure the "us_vhost_path" variable to point to the DPDK vhost-net sample code's character devices name. DPDK vhost-net sample code's character device will be in the format "/dev/-". .. code-block:: xml @@ -658,7 +723,7 @@ The number of free hugepages can be checked as follows: .. code-block:: console - user@target:cat /sys/kernel/mm/hugepages/hugepages- / nr_hugepages + 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.