Hello Bhanuprakash, few comments inline On Tue, Jun 7, 2016 at 6:45 PM, Bhanuprakash Bodireddy < bhanuprakash.bodire...@intel.com> wrote:
> Add INSTALL.DPDK-ADVANCED document that is forked off from original > INSTALL.DPDK guide. This document is targeted at users looking for > optimum performance on OVS using dpdk datapath. > > Signed-off-by: Bhanuprakash Bodireddy <bhanuprakash.bodire...@intel.com> > --- > INSTALL.DPDK-ADVANCED.md | 868 > +++++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 868 insertions(+) > create mode 100644 INSTALL.DPDK-ADVANCED.md > > diff --git a/INSTALL.DPDK-ADVANCED.md b/INSTALL.DPDK-ADVANCED.md > new file mode 100644 > index 0000000..f68476d > --- /dev/null > +++ b/INSTALL.DPDK-ADVANCED.md > @@ -0,0 +1,868 @@ > +OVS DPDK ADVANCED INSTALL GUIDE > +================================= > + > +## Contents > + > +1. [Overview](#overview) > +2. [Building Shared Library](#build) > +3. [System configuration](#sysconf) > +4. [Performance Tuning](#perftune) > +5. [OVS Testcases](#ovstc) > +6. [Vhost Walkthrough](#vhost) > +7. [QOS](#qos) > +8. [Rate Limiting](#rl) > +9. [Static Code Analysis](#staticanalyzer) > +10. [Vsperf](#vsperf) > + > +## <a name="overview"></a> 1. Overview > + > +The Advanced Install Guide explains how to improve OVS performance using > +DPDK datapath. This guide also provides information on tuning, system > configuration, > +troubleshooting, static code analysis and testcases. > + > +## <a name="build"></a> 2. Building Shared Library > + > +DPDK can be built as static or shared library and shall be linked by > applications > +using DPDK datapath. The section lists steps to build shared library and > dynamically > +link DPDK against OVS. > + > +Note: Minor performance loss is seen with OVS when using shared DPDK > library as > +compared to static library. > + > +Check section [INSTALL DPDK], [INSTALL OVS] of INSTALL.DPDK on download > instructions > +for DPDK and OVS. > + > + * Configure the DPDK library > + > + Set `CONFIG_RTE_BUILD_SHARED_LIB=y` in `config/common_base` > + to generate shared DPDK library > + > + > + * Build and install DPDK > + > + For Default install (without IVSHMEM), set `export > DPDK_TARGET=x86_64-native-linuxapp-gcc` > + For IVSHMEM case, set `export DPDK_TARGET=x86_64-ivshmem-linuxapp-gcc` > + > + ``` > + export DPDK_DIR=/usr/src/dpdk-16.04 > + export DPDK_BUILD=$DPDK_DIR/$DPDK_TARGET > + make install T=$DPDK_TARGET DESTDIR=install > + ``` > + > + * Build, Install and Setup OVS. > + > + Export the DPDK shared library location and setup OVS as listed in > + section 3.3 of INSTALL.DPDK. > + > + `export LD_LIBRARY_PATH=$DPDK_DIR/x86_64-native-linuxapp-gcc/lib` > + > +## <a name="sysconf"></a> 3. System Configuration > + > +To achieve optimal OVS performance, the system can be configured and that > includes > +BIOS tweaks, Grub cmdline additions, better understanding of NUMA nodes > and > +apt selection of PCIe slots for NIC placement. > + > +### 3.1 Recommended BIOS settings > + > + ``` > + | Settings | values | comments > + |---------------------------|-----------|----------- > + | C3 power state | Disabled | - > + | C6 power state | Disabled | - > + | MLC Streamer | Enabled | - > + | MLC Spacial prefetcher | Enabled | - > + | DCU Data prefetcher | Enabled | - > + | DCA | Enabled | - > + | CPU power and performance | Performance - > + | Memory RAS and perf | | - > + config-> NUMA optimized | Enabled | - > + ``` > + > +### 3.2 PCIe Slot Selection > + > +The fastpath performance also depends on factors like the NIC placement, > +Channel speeds between PCIe slot and CPU, proximity of PCIe slot to the > CPU > +cores running DPDK application. Listed below are the steps to identify > +right PCIe slot. > + > +- Retrieve host details using cmd `dmidecode -t baseboard | grep "Product > Name"` > +- Download the technical specification for Product listed eg: S2600WT2. > +- Check the Product Architecture Overview on the Riser slot placement, > + CPU sharing info and also PCIe channel speeds. > + > + example: On S2600WT, CPU1 and CPU2 share Riser Slot 1 with Channel > speed between > + CPU1 and Riser Slot1 at 32GB/s, CPU2 and Riser Slot1 at 16GB/s. Running > DPDK app > + on CPU1 cores and NIC inserted in to Riser card Slots will optimize OVS > performance > + in this case. > + > +- Check the Riser Card #1 - Root Port mapping information, on the > available slots > + and individual bus speeds. In S2600WT slot 1, slot 2 has high bus > speeds and are > + potential slots for NIC placement. > + > +### 3.3 Advanced Hugepage setup > + > + Allocate and mount 1G Huge pages: > + > + - For persistent allocation of huge pages, add the following options to > the kernel bootline > + > + Add `default_hugepagesz=1GB hugepagesz=1G hugepages=N` > + > + For platforms supporting multiple huge page sizes, Add options > + > + `default_hugepagesz=<size> hugepagesz=<size> hugepages=N` > + where 'N' = Number of huge pages requested, 'size' = huge page size, > + optional suffix [kKmMgG] > + > + - For run-time allocation of huge pages > + > + `echo N > > /sys/devices/system/node/nodeX/hugepages/hugepages-1048576kB/nr_hugepages` > + where 'N' = Number of huge pages requested, 'X' = NUMA Node > + > + Note: For run-time allocation of 1G huge pages, Contiguous Memory > Allocator(CONFIG_CMA) > + has to be supported by kernel, check your Linux distro. > + > + - Mount huge pages > + > + `mount -t hugetlbfs -o pagesize=1G none /dev/hugepages` > + > + Note: Mount hugepages if not already mounted by default. > + > +### 3.4 Enable Hyperthreading > + > + Requires BIOS changes > + > + With HT/SMT enabled, A Physical core appears as two logical cores. > + SMT can be utilized to spawn worker threads on logical cores of the same > + physical core there by saving additional cores. > + > + With DPDK, When pinning pmd threads to logical cores, care must be taken > + to set the correct bits in the pmd-cpu-mask to ensure that the pmd > threads are > + pinned to SMT siblings. > + > + Example System configuration: > + Dual socket Machine, 2x 10 core processors, HT enabled, 40 logical cores > + > + To use two logical cores which share the same physical core for pmd > threads, > + the following command can be used to identify a pair of logical cores. > + > + `cat /sys/devices/system/cpu/cpuN/topology/thread_siblings_list`, where > N is the > + logical core number. > + > + In this example, it would show that cores 1 and 21 share the same > physical core. > + The pmd-cpu-mask to enable two pmd threads running on these two logical > cores > + (one physical core) is. > + > + `ovs-vsctl set Open_vSwitch . other_config:pmd-cpu-mask=100002` > + > +### 3.5 Isolate cores > + > + 'isolcpus' option can be used to isolate cores from the linux scheduler. > + The isolated cores can then be used to dedicatedly run HPC > applications/threads. > + This helps in better application performance due to zero context > switching and > + minimal cache thrashing. To run platform logic on core 0 and isolate > cores > + between 1 and 19 from scheduler, Add `isolcpus=1-19` to GRUB cmdline. > + > + Note: It has been verified that core isolation has minimal advantage > due to > + mature Linux scheduler in some circumstances. > + > +### 3.6 NUMA/Cluster on Die > + > + Ideally inter NUMA datapaths should be avoided where possible as packets > + will go across QPI and there may be a slight performance penalty when > + compared with intra NUMA datapaths. On Intel Xeon Processor E5 v3, > + Cluster On Die is introduced on models that have 10 cores or more. > + This makes it possible to logically split a socket into two NUMA regions > + and again it is preferred where possible to keep critical datapaths > + within the one cluster. > + > + It is good practice to ensure that threads that are in the datapath are > + pinned to cores in the same NUMA area. e.g. pmd threads and QEMU vCPUs > + responsible for forwarding. > + > +### 3.7 Compiler Optimizations > + > + The default compiler optimization level is '-O2'. Changing this to > + more aggressive compiler optimization such as '-O3 -march=native' > + with gcc(verified on 5.3.1) can produce performance gains though not > + siginificant. '-march=native' will produce optimized code on local > machine > + and should be used when SW compilation is done on Testbed. > + > +## <a name="perftune"></a> 4. Performance Tuning > + > Reading section 3 I feel all the setting are oriented to the performance, then what is the difference between section 3 and 4? +### 4.1 Affinity > + > +For superior performance, DPDK pmd threads and Qemu vCPU threads > +needs to be affinitized accordingly. > + > + * PMD thread Affinity > + > + A poll mode driver (pmd) thread handles the I/O of all DPDK > + interfaces assigned to it. A pmd thread shall poll the ports > + for incoming packets, switch the packets and send to tx port. > + pmd thread is CPU bound, and needs to be affinitized to isolated > + cores for optimum performance. > + > + By setting a bit in the mask, a pmd thread is created and pinned > + to the corresponding CPU core. e.g. to run a pmd thread on core 2 > + > + `ovs-vsctl set Open_vSwitch . other_config:pmd-cpu-mask=4` > + > + Note: pmd thread on a NUMA node is only created if there is > + at least one DPDK interface from that NUMA node added to OVS. > + > + * Qemu vCPU thread Affinity > + > + A VM performing simple packet forwarding or running complex packet > + pipelines has to ensure that the vCPU threads performing the work has > + as much CPU occupancy as possible. > + > + Example: On a multicore VM, multiple QEMU vCPU threads shall be > spawned. > + when the DPDK 'testpmd' application that does packet forwarding > + is invoked, 'taskset' cmd should be used to affinitize the vCPU > threads > + to the dedicated isolated cores on the host system. > + > +### 4.2 Multiple poll mode driver threads > + > + With pmd multi-threading support, OVS creates one pmd thread > + for each NUMA node by default. However, it can be seen that in cases > + where there are multiple ports/rxq's producing traffic, performance > + can be improved by creating multiple pmd threads running on separate > + cores. These pmd threads can then share the workload by each being > + responsible for different ports/rxq's. Assignment of ports/rxq's to > + pmd threads is done automatically. > + > + A set bit in the mask means a pmd thread is created and pinned > + to the corresponding CPU core. e.g. to run pmd threads on core 1 and 2 > + > + `ovs-vsctl set Open_vSwitch . other_config:pmd-cpu-mask=6` > + > + For example, when using dpdk and dpdkvhostuser ports in a bi-directional > + VM loopback as shown below, spreading the workload over 2 or 4 pmd > + threads shows significant improvements as there will be more total CPU > + occupancy available. > + > + NIC port0 <-> OVS <-> VM <-> OVS <-> NIC port 1 > + > +### 4.3 DPDK port Rx Queues > + > + `ovs-vsctl set Interface <DPDK interface> options:n_rxq=<integer>` > + > + The command above sets the number of rx queues for DPDK interface. > + The rx queues are assigned to pmd threads on the same NUMA node in a > + round-robin fashion. For more information, please refer to the > + Open_vSwitch TABLE section in > + > + `man ovs-vswitchd.conf.db` > + > +### 4.4 Exact Match Cache > + > + Each pmd thread contains one EMC. After initial flow setup in the > + datapath, the EMC contains a single table and provides the lowest level > + (fastest) switching for DPDK ports. If there is a miss in the EMC then > + the next level where switching will occur is the datapath classifier. > + Missing in the EMC and looking up in the datapath classifier incurs a > + significant performance penalty. If lookup misses occur in the EMC > + because it is too small to handle the number of flows, its size can > + be increased. The EMC size can be modified by editing the define > + EM_FLOW_HASH_SHIFT in lib/dpif-netdev.c. > + > + As mentioned above an EMC is per pmd thread. So an alternative way of > + increasing the aggregate amount of possible flow entries in EMC and > + avoiding datapath classifier lookups is to have multiple pmd threads > + running. This can be done as described in section 4.2. > + > +### 4.5 Rx Mergeable buffers > + > + Rx Mergeable buffers is a virtio feature that allows chaining of > multiple > + virtio descriptors to handle large packet sizes. As such, large packets > + are handled by reserving and chaining multiple free descriptors > + together. Mergeable buffer support is negotiated between the virtio > + driver and virtio device and is supported by the DPDK vhost library. > + This behavior is typically supported and enabled by default, however > + in the case where the user knows that rx mergeable buffers are not > needed > + i.e. jumbo frames are not needed, it can be forced off by adding > + mrg_rxbuf=off to the QEMU command line options. By not reserving > multiple > + chains of descriptors it will make more individual virtio descriptors > + available for rx to the guest using dpdkvhost ports and this can improve > + performance. > + > +## <a name="ovstc"></a> 5. OVS Testcases > +### 5.1 PHY-VM-PHY [VHOST LOOPBACK] > + > +The section 5.2 in INSTALL.DPDK guide lists steps for PVP loopback > testcase > +and packet forwarding using DPDK testpmd application in the Guest VM. > +For users wanting to do packet forwarding using kernel stack below are > the steps. > + > + ``` > + ifconfig eth1 1.1.1.2/24 > + ifconfig eth2 1.1.2.2/24 > + systemctl stop firewalld.service > + systemctl stop iptables.service > + sysctl -w net.ipv4.ip_forward=1 > + sysctl -w net.ipv4.conf.all.rp_filter=0 > + sysctl -w net.ipv4.conf.eth1.rp_filter=0 > + sysctl -w net.ipv4.conf.eth2.rp_filter=0 > + route add -net 1.1.2.0/24 eth2 > + route add -net 1.1.1.0/24 eth1 > + arp -s 1.1.2.99 DE:AD:BE:EF:CA:FE > + arp -s 1.1.1.99 DE:AD:BE:EF:CA:EE > + ``` > + > +### 5.2 PHY-VM-PHY [IVSHMEM] > + > + The steps (1-5) in 3.3 section of INSTALL.DPDK guide will create & > initialize DB, > + start vswitchd and add dpdk devices to bridge br0. > + > + 1. Add DPDK ring port to the bridge > + > + ``` > + ovs-vsctl add-port br0 dpdkr0 -- set Interface dpdkr0 type=dpdkr > + ``` > + > + 2. Build modified Qemu (Qemu-2.2.1 + ivshmem-qemu-2.2.1.patch) > + > + ``` > + cd /usr/src/ > + wget http://wiki.qemu.org/download/qemu-2.2.1.tar.bz2 > + tar -jxvf qemu-2.2.1.tar.bz2 > + cd /usr/src/qemu-2.2.1 > + wget > https://raw.githubusercontent.com/netgroup-polito/un-orchestrator/master/orchestrator/compute_controller/plugins/kvm-libvirt/patches/ivshmem-qemu-2.2.1.patch > + patch -p1 < ivshmem-qemu-2.2.1.patch > + ./configure --target-list=x86_64-softmmu --enable-debug > --extra-cflags='-g' > + make -j 4 > + ``` > + > + 3. Generate Qemu commandline > + > + ``` > + mkdir -p /usr/src/cmdline_generator > + cd /usr/src/cmdline_generator > + wget > https://raw.githubusercontent.com/netgroup-polito/un-orchestrator/master/orchestrator/compute_controller/plugins/kvm-libvirt/cmdline_generator/cmdline_generator.c > + wget > https://raw.githubusercontent.com/netgroup-polito/un-orchestrator/master/orchestrator/compute_controller/plugins/kvm-libvirt/cmdline_generator/Makefile > + export RTE_SDK=/usr/src/dpdk-16.04 > + export RTE_TARGET=x86_64-ivshmem-linuxapp-gcc > + make > + ./build/cmdline_generator -m -p dpdkr0 XXX > + cmdline=`cat OVSMEMPOOL` > + ``` > + > + 4. start Guest VM > + > + ``` > + export VM_NAME=ivshmem-vm > + export QCOW2_IMAGE=/root/CentOS7_x86_64.qcow2 > + export > QEMU_BIN=/usr/src/qemu-2.2.1/x86_64-softmmu/qemu-system-x86_64 > + > + taskset 0x20 $QEMU_BIN -cpu host -smp 2,cores=2 -hda $QCOW2_IMAGE > -m 4096 --enable-kvm -name $VM_NAME -nographic -vnc :2 -pidfile > /tmp/vm1.pid $cmdline > + ``` > + > + 5. Running sample "dpdk ring" app in VM > + > + ``` > + echo 1024 > /proc/sys/vm/nr_hugepages > + mount -t hugetlbfs nodev /dev/hugepages (if not already mounted) > + > + # Build the DPDK ring application in the VM > + export RTE_SDK=/root/dpdk-16.04 > + export RTE_TARGET=x86_64-ivshmem-linuxapp-gcc > + make > + > + # Run dpdkring application > + ./build/dpdkr -c 1 -n 4 -- -n 0 > + where "-n 0" refers to ring '0' i.e dpdkr0 > + ``` > + > +## <a name="vhost"></a> 6. Vhost Walkthrough > + > +DPDK 16.04 supports two types of vhost: > + > +1. vhost-user - enabled default > + > +2. vhost-cuse - Legacy, disabled by default > + > +### 6.1 vhost-user > + > + - Prerequisites: > + > + QEMU version >= 2.2 > + > + - Adding vhost-user ports to Switch > + > + Unlike DPDK ring ports, DPDK vhost-user ports can have arbitrary > names, > + except that forward and backward slashes are prohibited in the names. > + > + For vhost-user, the name of the port type is `dpdkvhostuser` > + > + ``` > + ovs-vsctl add-port br0 vhost-user-1 -- set Interface vhost-user-1 > + type=dpdkvhostuser > + ``` > + > + This action creates a socket located at > + `/usr/local/var/run/openvswitch/vhost-user-1`, which you must provide > + to your VM on the QEMU command line. More instructions on this can be > + found in the next section "Adding vhost-user ports to VM" > + > + Note: If you wish for the vhost-user sockets to be created in a > + sub-directory of `/usr/local/var/run/openvswitch`, you may specify > + this directory in the ovsdb like so: > + > + `./utilities/ovs-vsctl --no-wait \ > + set Open_vSwitch . other_config:vhost-sock-dir=subdir` > + > + - Adding vhost-user ports to VM > + > + 1. Configure sockets > + > + Pass the following parameters to QEMU to attach a vhost-user > device: > + > + ``` > + -chardev > socket,id=char1,path=/usr/local/var/run/openvswitch/vhost-user-1 > + -netdev type=vhost-user,id=mynet1,chardev=char1,vhostforce > + -device virtio-net-pci,mac=00:00:00:00:00:01,netdev=mynet1 > + ``` > + > + where vhost-user-1 is the name of the vhost-user port added > + to the switch. > + Repeat the above parameters for multiple devices, changing the > + chardev path and id as necessary. Note that a separate and > different > + chardev path needs to be specified for each vhost-user device. For > + example you have a second vhost-user port named 'vhost-user-2', you > + append your QEMU command line with an additional set of parameters: > + > + ``` > + -chardev > socket,id=char2,path=/usr/local/var/run/openvswitch/vhost-user-2 > + -netdev type=vhost-user,id=mynet2,chardev=char2,vhostforce > + -device virtio-net-pci,mac=00:00:00:00:00:02,netdev=mynet2 > + ``` > + > + 2. Configure huge pages. > + > + QEMU must allocate the VM's memory on hugetlbfs. vhost-user ports > access > + a virtio-net device's virtual rings and packet buffers mapping the > VM's > + physical memory on hugetlbfs. To enable vhost-user ports to map > the VM's > + memory into their process address space, pass the following > parameters > + to QEMU: > + > + ``` > + -object > memory-backend-file,id=mem,size=4096M,mem-path=/dev/hugepages, > + share=on -numa node,memdev=mem -mem-prealloc > + ``` > + > + 3. Enable multiqueue support(OPTIONAL) > + > + The vhost-user interface must be configured in Open vSwitch with > the > + desired amount of queues with: > + > + ``` > + ovs-vsctl set Interface vhost-user-2 options:n_rxq=<requested > queues> > + ``` > + > + QEMU needs to be configured as well. > + The $q below should match the queues requested in OVS (if $q is > more, > + packets will not be received). > + The $v is the number of vectors, which is '$q x 2 + 2'. > + > + ``` > + -chardev > socket,id=char2,path=/usr/local/var/run/openvswitch/vhost-user-2 > + -netdev > type=vhost-user,id=mynet2,chardev=char2,vhostforce,queues=$q > + -device > virtio-net-pci,mac=00:00:00:00:00:02,netdev=mynet2,mq=on,vectors=$v > + ``` > + > + If one wishes to use multiple queues for an interface in the > guest, the > + driver in the guest operating system must be configured to do so. > It is > + recommended that the number of queues configured be equal to '$q'. > + > + For example, this can be done for the Linux kernel virtio-net > driver with: > + > + ``` > + ethtool -L <DEV> combined <$q> > + ``` > + where `-L`: Changes the numbers of channels of the specified > network device > + and `combined`: Changes the number of multi-purpose channels. > + > + - VM Configuration with libvirt > + > + * change the user/group, access control policty and restart libvirtd. > + > + - In `/etc/libvirt/qemu.conf` add/edit the following lines > + > + ``` > + user = "root" > + group = "root" > + ``` > + > + - Disable SELinux or set to permissive mode > + > + `setenforce 0` > + > + - Restart the libvirtd process, For example, on Fedora > + > + `systemctl restart libvirtd.service` > + > + * Instantiate the VM > + > + - Copy the xml configuration from [Guest VM using libvirt] in to > workspace. > + > + - Start the VM. > + > + `virsh create demovm.xml` > + > + - Connect to the guest console > + > + `virsh console demovm` > + > + * VM configuration > + > + The demovm xml configuration is aimed at achieving out of box > performance > + on VM. > + > + - The vcpus are pinned to the cores of the CPU socket 0 using > vcpupin. > + > + - Configure NUMA cell and memory shared using memAccess='shared'. > + > + - Disable mrg_rxbuf='off'. > + > + Note: For information on libvirt and further tuning refer [libvirt]. > + > +### 6.2 vhost-cuse > + > + - Prerequisites: > + > + QEMU version >= 2.2 > + > + - Enable vhost-cuse support > + > + 1. Enable vhost cuse support in DPDK > + > + Set `CONFIG_RTE_LIBRTE_VHOST_USER=n` in config/common_linuxapp and > follow the > + steps in 2.2 section of INSTALL.DPDK guide to build DPDK with cuse > support. > + OVS will detect that DPDK has vhost-cuse libraries compiled and in > turn will enable > + support for it in the switch and disable vhost-user support. > + > + 2. Insert the Cuse module > + > + `modprobe cuse` > + > + 3. Build and insert the `eventfd_link` module > + > + ``` > + cd $DPDK_DIR/lib/librte_vhost/eventfd_link/ > + make > + insmod $DPDK_DIR/lib/librte_vhost/eventfd_link.ko > + ``` > + > + - Adding vhost-cuse ports to Switch > + > + Unlike DPDK ring ports, DPDK vhost-cuse ports can have arbitrary > names. > + For vhost-cuse, the name of the port type is `dpdkvhostcuse` > + > + ``` > + ovs-vsctl add-port br0 vhost-cuse-1 -- set Interface vhost-cuse-1 > + type=dpdkvhostcuse > + ``` > + > + When attaching vhost-cuse ports to QEMU, the name provided during the > + add-port operation must match the ifname parameter on the QEMU cmd > line. > + > + - Adding vhost-cuse ports to VM > + > + vhost-cuse ports use a Linux* character device to communicate with > QEMU. > + By default it is set to `/dev/vhost-net`. It is possible to reuse this > + standard device for DPDK vhost, which makes setup a little simpler > but it > + is better practice to specify an alternative character device in > order to > + avoid any conflicts if kernel vhost is to be used in parallel. > + > + 1. This step is only needed if using an alternative character device. > + > + ``` > + ./utilities/ovs-vsctl --no-wait set Open_vSwitch . \ > + other_config:cuse-dev-name=my-vhost-net > + ``` > + > + In the example above, the character device to be used will be > + `/dev/my-vhost-net`. > + > + 2. In case of reusing kernel vhost character device, there would be > conflict > + user should remove it. > + > + `rm -rf /dev/vhost-net` > + > + 3. Configure virtio-net adapters > + > + The following parameters must be passed to the QEMU binary, repeat > + the below parameters for multiple devices. > + > + ``` > + -netdev tap,id=<id>,script=no,downscript=no,ifname=<name>,vhost=on > + -device virtio-net-pci,netdev=net1,mac=<mac> > + ``` > + > + The DPDK vhost library will negotiate its own features, so they > + need not be passed in as command line params. Note that as offloads > + are disabled this is the equivalent of setting > + > + `csum=off,gso=off,guest_tso4=off,guest_tso6=off,guest_ecn=off` > + > + When using an alternative character device, it must be explicitly > + passed to QEMU using the `vhostfd` argument > + > + ``` > + -netdev tap,id=<id>,script=no,downscript=no,ifname=<name>,vhost=on, > + vhostfd=<open_fd> -device virtio-net-pci,netdev=net1,mac=<mac> > + ``` > + > + The open file descriptor must be passed to QEMU running as a child > + process. This could be done with a simple python script. > + > + ``` > + #!/usr/bin/python > + fd = os.open("/dev/usvhost", os.O_RDWR) > + subprocess.call("qemu-system-x86_64 .... -netdev tap,id=vhostnet0,\ > + vhost=on,vhostfd=" + fd +"...", shell=True) > + ``` > + > + 4. Configure huge pages > + > + QEMU must allocate the VM's memory on hugetlbfs. Vhost ports > access a > + virtio-net device's virtual rings and packet buffers mapping the > VM's > + physical memory on hugetlbfs. To enable vhost-ports to map the VM's > + memory into their process address space, pass the following > parameters > + to QEMU > + > + `-object > memory-backend-file,id=mem,size=4096M,mem-path=/dev/hugepages, > + share=on -numa node,memdev=mem -mem-prealloc` > + > + - VM Configuration with QEMU wrapper > + > + The QEMU wrapper script automatically detects and calls QEMU with the > + necessary parameters. It performs the following actions: > + > + * Automatically detects the location of the hugetlbfs and inserts this > + into the command line parameters. > + * Automatically open file descriptors for each virtio-net device and > + inserts this into the command line parameters. > + * Calls QEMU passing both the command line parameters passed to the > + script itself and those it has auto-detected. > + > + Before use, you **must** edit the configuration parameters section of > the > + script to point to the correct emulator location and set additional > + settings. Of these settings, `emul_path` and `us_vhost_path` **must** > be > + set. All other settings are optional. > + > + To use directly from the command line simply pass the wrapper some of > the > + QEMU parameters: it will configure the rest. For example: > + > + ``` > + qemu-wrap.py -cpu host -boot c -hda <disk image> -m 4096 -smp 4 > + --enable-kvm -nographic -vnc none -net none -netdev tap,id=net1, > + script=no,downscript=no,ifname=if1,vhost=on -device virtio-net-pci, > + netdev=net1,mac=00:00:00:00:00:01 > + ``` > + > + - VM Configuration with libvirt > + > + If you are using libvirt, you must enable libvirt to access the > character > + device by adding it to controllers cgroup for libvirtd using the > following > + steps. > + > + 1. In `/etc/libvirt/qemu.conf` add/edit the following lines: > + > + ``` > + clear_emulator_capabilities = 0 > + user = "root" > + group = "root" > + cgroup_device_acl = [ > + "/dev/null", "/dev/full", "/dev/zero", > + "/dev/random", "/dev/urandom", > + "/dev/ptmx", "/dev/kvm", "/dev/kqemu", > + "/dev/rtc", "/dev/hpet", "/dev/net/tun", > + "/dev/<my-vhost-device>", > + "/dev/hugepages"] > + ``` > + > + <my-vhost-device> refers to "vhost-net" if using the > `/dev/vhost-net` > + device. If you have specificed a different name in the database > + using the "other_config:cuse-dev-name" parameter, please specify > that > + filename instead. > + > + 2. Disable SELinux or set to permissive mode > + > + 3. Restart the libvirtd process > + For example, on Fedora: > + > + `systemctl restart libvirtd.service` > + > + After successfully editing the configuration, you may launch your > + vhost-enabled VM. The XML describing the VM can be configured like so > + within the <qemu:commandline> section: > + > + 1. Set up shared hugepages: > + > + ``` > + <qemu:arg value='-object'/> > + <qemu:arg > value='memory-backend-file,id=mem,size=4096M,mem-path=/dev/hugepages,share=on'/> > + <qemu:arg value='-numa'/> > + <qemu:arg value='node,memdev=mem'/> > + <qemu:arg value='-mem-prealloc'/> > + ``` > + > + 2. Set up your tap devices: > + > + ``` > + <qemu:arg value='-netdev'/> > + <qemu:arg > value='type=tap,id=net1,script=no,downscript=no,ifname=vhost0,vhost=on'/> > + <qemu:arg value='-device'/> > + <qemu:arg > value='virtio-net-pci,netdev=net1,mac=00:00:00:00:00:01'/> > + ``` > + > + Repeat for as many devices as are desired, modifying the id, ifname > + and mac as necessary. > + > + Again, if you are using an alternative character device (other than > + `/dev/vhost-net`), please specify the file descriptor like so: > + > + `<qemu:arg > value='type=tap,id=net3,script=no,downscript=no,ifname=vhost0,vhost=on,vhostfd=<open_fd>'/>` > + > + Where <open_fd> refers to the open file descriptor of the character > device. > + Instructions of how to retrieve the file descriptor can be found in > the > + "DPDK vhost VM configuration" section. > + Alternatively, the process is automated with the qemu-wrap.py script, > + detailed in the next section. > + > + Now you may launch your VM using virt-manager, or like so: > + > + `virsh create my_vhost_vm.xml` > + > + - VM Configuration with libvirt & QEMU wrapper > + > + To use the qemu-wrapper script in conjuntion with libvirt, follow the > + steps in the previous section before proceeding with the following > steps: > + > + 1. Place `qemu-wrap.py` in libvirtd binary search PATH ($PATH) > + Ideally in the same directory that the QEMU binary is located. > + > + 2. Ensure that the script has the same owner/group and file > permissions > + as the QEMU binary. > + > + 3. Update the VM xml file using "virsh edit VM.xml" > + > + Set the VM to use the launch script. > + Set the emulator path contained in the `<emulator><emulator/>` > tags. > + For example, replace `<emulator>/usr/bin/qemu-kvm<emulator/>` with > + `<emulator>/usr/bin/qemu-wrap.py<emulator/>` > + > + 4. Edit the Configuration Parameters section of the script to point to > + the correct emulator location and set any additional options. If > you are > + using a alternative character device name, please set > "us_vhost_path" to the > + location of that device. The script will automatically detect and > insert > + the correct "vhostfd" value in the QEMU command line arguments. > + > + 5. Use virt-manager to launch the VM > + > +### 6.3 DPDK backend inside VM > + > + Please note that additional configuration is required if you want to run > + ovs-vswitchd with DPDK backend inside a QEMU virtual machine. > Ovs-vswitchd > + creates separate DPDK TX queues for each CPU core available. This > operation > + fails inside QEMU virtual machine because, by default, VirtIO NIC > provided > + to the guest is configured to support only single TX queue and single RX > + queue. To change this behavior, you need to turn on 'mq' (multiqueue) > + property of all virtio-net-pci devices emulated by QEMU and used by > DPDK. > + You may do it manually (by changing QEMU command line) or, if you use > + Libvirt, by adding the following string: > + > + `<driver name='vhost' queues='N'/>` > + > + to <interface> sections of all network devices used by DPDK. Parameter > 'N' > + determines how many queues can be used by the guest.This may not work > with > + old versions of QEMU found in some distros and need Qemu version >= 2.2. > + > +## <a name="qos"></a> 7. QOS > + > +Here is an example on QOS usage. > +Assuming you have a vhost-user port transmitting traffic consisting of > +packets of size 64 bytes, the following command would limit the egress > +transmission rate of the port to ~1,000,000 packets per second > + > +`ovs-vsctl set port vhost-user0 qos=@newqos -- --id=@newqos create qos > +type=egress-policer other-config:cir=46000000 other-config:cbs=2048` > + > +To examine the QoS configuration of the port: > + > +`ovs-appctl -t ovs-vswitchd qos/show vhost-user0` > + > +To clear the QoS configuration from the port and ovsdb use the following: > + > +`ovs-vsctl destroy QoS vhost-user0 -- clear Port vhost-user0 qos` > + > +For more details regarding egress-policer parameters please refer to the > +vswitch.xml. > + > +## <a name="rl"></a> 8. Rate Limiting > + > +Here is an example on Ingress Policing usage. > +Assuming you have a vhost-user port receiving traffic consisting of > +packets of size 64 bytes, the following command would limit the reception > +rate of the port to ~1,000,000 packets per second: > + > +`ovs-vsctl set interface vhost-user0 ingress_policing_rate=368000 > + ingress_policing_burst=1000` > + > +To examine the ingress policer configuration of the port: > + > +`ovs-vsctl list interface vhost-user0` > + > +To clear the ingress policer configuration from the port use the > following: > + > +`ovs-vsctl set interface vhost-user0 ingress_policing_rate=0` > + > +For more details regarding ingress-policer see the vswitch.xml. > + > +## <a name="staticanalyzer"></a> 9. Static Code Analysis > + > +Static Analysis is method of debugging SW by examining the code rather > than > +actually executing it. Many third party Software is available to carry > +Static analysis, few being open source and rest commercial. > + > +Below are the steps to run clang static analyzer on OVS codebase. > + > + ``` > + apt-get install clang [ On Ubuntu] > + dnf install clang clang-analyzer -y [ On fedora] > + > + cd $OVS_DIR > + ./boot.sh > + ./configure --with-dpdk > + make clean > + scan-build make CFLAGS="-std=gnu99" > + scan-view --host=<ip address> --port 8183 > /tmp/scan-build-yyyy-mm-dd-114251-1027-1 --allow-all-hosts > + ``` > + > + The results can be viewed on the browser using ip address and port no. > + > + `http://<ip address>:8183/` > + > +## <a name="vsperf"></a> 10. Vsperf > + > +Vsperf project goal is to develop vSwitch test framework that can be used > to > +validate the suitability of different vSwitch implementations in a Telco > deployment > +environment. More information can be found in below link. > + > +https://wiki.opnfv.org/display/vsperf/VSperf+Home > + > + > +Bug Reporting: > +-------------- > + > +Please report problems to b...@openvswitch.org. > + > + > +[INSTALL.userspace.md]:INSTALL.userspace.md > +[INSTALL.md]:INSTALL.md > +[DPDK Linux GSG]: > http://www.dpdk.org/doc/guides/linux_gsg/build_dpdk.html#binding-and-unbinding-network-ports-to-from-the-igb-uioor-vfio-modules > +[DPDK Docs]: http://dpdk.org/doc > +[libvirt]: http://libvirt.org/formatdomain.html > +[Guest VM using libvirt]: INSTALL.DPDK.md#ovstc > +[INSTALL DPDK]: INSTALL.DPDK.md#build > +[INSTALL OVS]: INSTALL.DPDK.md#build > -- > 2.4.11 > > Best Regards, Mauricio V _______________________________________________ dev mailing list dev@openvswitch.org http://openvswitch.org/mailman/listinfo/dev
