From b04935b08394a9b64b69429215e27f0323065bfa Mon Sep 17 00:00:00 2001 From: kalyanreddy Date: Tue, 28 Mar 2017 11:34:11 +0530 Subject: Update documentation structure. This patch is used to update documentation structure. Change-Id: I50d4ef4256ccfc57a0434123e7532a50000582cf Co-Authored by:Srinivas Co-Authored by:RajithaY Co-Authored by:shravani paladugula Co-Authored by:Navya Bathula Signed-off-by: Gundarapu Kalyan Reddy (cherry picked from commit f1f3cc27f23bdde81c37d8142d4288d811bd5e45) --- docs/design/kvmfornfv_design.rst | 136 --------------------------------------- 1 file changed, 136 deletions(-) delete mode 100644 docs/design/kvmfornfv_design.rst (limited to 'docs/design/kvmfornfv_design.rst') diff --git a/docs/design/kvmfornfv_design.rst b/docs/design/kvmfornfv_design.rst deleted file mode 100644 index 765f41219..000000000 --- a/docs/design/kvmfornfv_design.rst +++ /dev/null @@ -1,136 +0,0 @@ -.. This work is licensed under a Creative Commons Attribution 4.0 International License. -.. http://creativecommons.org/licenses/by/4.0 - -========================== -KVM4NFV design description -========================== - -This design focuses on the enhancement of following area for KVM Hypervisor - -* Minimal Interrupt latency variation for data plane VNFs: - * Minimal Timing Variation for Timing correctness of real-time VNFs - * Minimal packet latency variation for data-plane VNFs -* Fast live migration - -**Minimal Interrupt latency variation for data plane VNFs** - -Processing performance and latency depend on a number of factors, including -the CPUs (frequency, power management features, etc.), micro-architectural -resources, the cache hierarchy and sizes, memory (and hierarchy, such as NUMA) -and speed, inter-connects, I/O and I/O NUMA, devices, etc. - -There are two separate types of latencies to minimize: - - 1. Minimal Timing Variation for Timing correctness of real-time - VNFs – timing correctness for scheduling operations(such as Radio scheduling) - 2. Minimal packet latency variation for data-plane VNFs – packet delay - variation, which applies to packet processing. - -For a VM, interrupt latency (time between arrival of H/W interrupt and -invocation of the interrupt handler in the VM), for example, can be either of -the above or both, depending on the type of the device. Interrupt latency with -a (virtual) timer can cause timing correctness issues with real-time VNFs even -if they only use polling for packet processing. - -We assume that the VNFs are implemented properly to minimize interrupt latency -variation within the VMs, but we have additional causes of latency variation -on KVM: - - - Asynchronous (e.g. external interrupts) and synchronous(e.g. instructions) - VM exits and handling in KVM (and kernel routines called), which may have - loops and spin locks - - Interrupt handling in the host Linux and KVM, scheduling and virtual - interrupt delivery to VNFs - - Potential VM exit (e.g. EOI) in the interrupt service routines in VNFs - - Exit to the user-level (e.g. QEMU) - -.. Figure:: kvm1.png - - -Design Considerations ---------------------- - -The latency variation and jitters can be minimized with the below -steps (with some in parallel): - - 1. Statically and exclusively assign hardware resources - (CPUs, memory, caches,) to the VNFs. - - 2. Pre-allocate huge pages (e.g. 1 GB/2MB pages) and guest-to-host mapping, - e.g. EPT (Extended Page Table) page tables, to minimize or mitigate - latency from misses in caches, - - 3. Use the host Linux configured for hard real-time and packet latency, - Check the set of virtual devices used by the VMs to optimize or - eliminate virtualization overhead if applicable - - 4. Use advanced hardware virtualization features that can reduce or - eliminate VM exits, if present, and - - 5. Inspect the code paths in KVM and associated kernel services to - eliminate code that can cause latencies (e.g. loops and spin locks). - - 6. Measure latencies intensively. We leverage the existing testing methods. - OSADL, for example, defines industry tests for timing correctness. - - -Goals and Guidelines --------------------- - -The output of this project will provide : - - 1. A list of the performance goals, which will be obtained by the - OPNFV members (as described above) - - 2. A set of comprehensive instructions for the system configurations - (hardware features, BIOS setup, kernel parameters, VM configuration, - options to QEMU/KVM, etc.) - - 3. The above features to the upstream of Linux, the real-time patch - set, KVM, QEMU, libvirt, and - - 4. Performance and interrupt latency measurement tools - - -Test plan ---------- - -The tests that need to be conducted to make sure that all components from OPNFV -meet the requirement are mentioned below: - -**Timer test**:This test utilize the cyclictest -(https://rt.wiki.kernel.org/index.php/Cyclictest) to test the guest timer -latency (the latency from the time that the guest timer should be triggered -to the time the guest timer is really triggered). - -.. Figure:: TimerTest.png - -**Device Interrupt Test**:A device on the hardware platform trigger interrupt -every one ms and the device interrupt will be delivered to the VNF. This test -cover the latency from the interrupt happened on the hardware to the time the -interrupt handled in the VNF. - -.. Figure:: DeviceInterruptTest.png - -**Packet forwarding (DPDK OVS)**:A packet is sent from TG (Traffic Generator) -to a VNF. The VNF, after processing the packet, forwards the packet to another -NIC and in the end the packet is received by the traffic generator. The test -check the latency from the packet is sent out by the TC to the time the packet -is received by the TC. - -.. Figure:: PacketforwardingDPDK_OVS.png - -**Packet Forwarding (SR-IOV)**:This test is similar to Packet Forwarding -(DPDK OVS). However, instead of using virtio NIC devices on the guest, -a PCI NIC or a PCI VF NIC is assigned to the guest for network acess. - -**Bare-metal Packet Forwarding**:This is used to compare with the above -packet forwarding scenario. - -.. Figure:: Bare-metalPacketForwarding.png - ----------- -Reference ----------- - -https://wiki.opnfv.org/display/kvm/ -- cgit 1.2.3-korg