--- /dev/null
+Low Latency Environment
+=======================
+
+Achieving low latency with the KVM4NFV project requires setting up a special
+test environment. This environment includes the BIOS settings, kernel
+configuration, kernel parameters and the run-time environment.
+
+Hardware Environment Description
+--------------------------------
+
+BIOS setup plays an important role in achieving real-time latency. A collection
+of relevant settings, used on the platform where the baseline performance data
+was collected, is detailed below:
+
+CPU Features
+~~~~~~~~~~~~
+
+Some special CPU features like TSC-deadline timer, invariant TSC and Process posted
+interrupts etc are helpful for latency reduction.
+
+Below is the CPU information on the baseline test platform.
+::
+ processor : 35
+ vendor_id : GenuineIntel
+ cpu family : 6
+ model : 63
+ model name : Intel(R) Xeon(R) CPU E5-2699 v3 @ 2.30GHz
+ stepping : 2
+ microcode : 0x2d
+ cpu MHz : 2294.795
+ cache size : 46080 KB
+ physical id : 1
+ siblings : 18
+ core id : 27
+ cpu cores : 18
+ apicid : 118
+ initial apicid : 118
+ fpu : yes
+ fpu_exception : yes
+ cpuid level : 15
+ wp : yes
+ flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge
+ mca cmov pat pse36 clflush dts acpi mmx fxsr sse
+ sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm
+ constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc
+ aperfmperf eagerfpu pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2
+ ssse3 fma cx16 xtpr pdcm pcid dca sse4_1 sse4_2 x2apic movbe popcnt
+ tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm abm arat epb
+ pln pts dtherm tpr_shadow vnmi flexpriority ept vpid fsgsbase
+ tsc_adjust bmi1 avx2 smep bmi2 erms invpcid cqm xsaveopt cqm_llc
+ cqm_occup_llcbugs
+ bogomips : 4595.54
+ clflush size : 64
+ cache_alignment : 64
+ address sizes : 46 bits physical, 48 bits virtual
+ power management:
+
+CPU Topology
+~~~~~~~~~~~~
+
+NUMA topology is also important for latency reducation.
+
+Below is the CPU topology on the baseline test platform.
+::
+ [nfv@otcnfv02 ~]$ lscpu
+ Architecture: x86_64
+ CPU op-mode(s): 32-bit, 64-bit
+ Byte Order: Little Endian
+ CPU(s): 36
+ On-line CPU(s) list: 0-35
+ Thread(s) per core: 1
+ Core(s) per socket: 18
+ Socket(s): 2
+ NUMA node(s): 2
+ Vendor ID: GenuineIntel
+ CPU family: 6
+ Model: 63
+ Model name: Intel(R) Xeon(R) CPU E5-2699 v3 @ 2.30GHz
+ Stepping: 2
+ CPU MHz: 2294.795
+ BogoMIPS: 4595.54
+ Virtualization: VT-x
+ L1d cache: 32K
+ L1i cache: 32K
+ L2 cache: 256K
+ L3 cache: 46080K
+ NUMA node0 CPU(s): 0-17
+ NUMA node1 CPU(s): 18-35
+
+BIOS Setup
+~~~~~~~~~~
+
+Careful BIOS setup is important in achieving real time latency. Different
+platforms have different BIOS setups, below are the important BIOS settings on
+the platform used to collect the baseline performance data.
+::
+ CPU Power and Performance <Performance>
+ CPU C-State <Disabled>
+ C1E Autopromote <Disabled>
+ Processor C3 <Disabled>
+ Processor C6 <Disabled>
+ Select Memory RAS <Maximum Performance>
+ NUMA Optimized <Enabled>
+ Cluster-on-Die <Disabled>
+ Patrol Scrub <Disabled>
+ Demand Scrub <Disabled>
+ Correctable Error <10>
+ Intel(R) Hyper-Threading <Disabled>
+ Active Processor Cores <All>
+ Execute Disable Bit <Enabled>
+ Intel(R) Virtualization Technology <Enabled>
+ Intel(R) TXT <Disabled>
+ Enhanced Error Containment Mode <Disabled>
+ USB Controller <Enabled>
+ USB 3.0 Controller <Auto>
+ Legacy USB Support <Disabled>
+ Port 60/64 Emulation <Disabled>
+
+Software Environment Setup
+--------------------------
+Both the host and the guest environment need to be configured properly to
+reduce latency variations. Below are some suggested kernel configurations.
+The ci/envs/ directory gives etailed implementation on how to setup the
+environment.
+
+Kernel Parameter
+~~~~~~~~~~~~~~~~
+
+Please check the default kernel configuration in the source code at:
+kernel/arch/x86/configs/opnfv.config.
+
+Below is host kernel boot line example:
+::
+ isolcpus=11-15,31-35 nohz_full=11-15,31-35 rcu_nocbs=11-15,31-35 iommu=pt intel_iommu=on default_hugepagesz=1G hugepagesz=1G mce=off idle=poll intel_pstate=disable processor.max_cstate=1 pcie_asmp=off tsc=reliable
+
+Below is guest kernel boot line example
+::
+ isolcpus=1 nohz_full=1 rcu_nocbs=1 mce=off idle=poll default_hugepagesz=1G hugepagesz=1G
+
+Please refer to :doc:`tunning` for more explanation.
+
+Run-time Environment Setup
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Not only are special kernel parameters needed but a special run-time
+environment is also required. Please refer to :doc:`tunning` for more
+explanation.
Code Review / kvmfornfv.git / blobdiff