Linux Kernel Support
~~~~~~~~~~~~~~~~~~~~
-The Intel® DPDK makes use of the platform HPET timer by mapping the timer counter into the process address space, and as such,
+The DPDK makes use of the platform HPET timer by mapping the timer counter into the process address space, and as such,
requires that the HPET_MMAP kernel configuration option be enabled.
.. warning::
On Fedora*, and other common distributions such as Ubuntu*, the HPET_MMAP kernel option is not enabled by default.
To recompile the Linux kernel with this option enabled, please consult the distributions documentation for the relevant instructions.
-Enabling HPET in the Intel® DPDK
+Enabling HPET in the DPDK
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-By default, HPET support is disabled in the Intel® DPDK build configuration files.
+By default, HPET support is disabled in the DPDK build configuration files.
To use HPET, the CONFIG_RTE_LIBEAL_USE_HPET setting should be changed to “y”, which will enable the HPET settings at compile time.
For an application to use the rte_get_hpet_cycles() and rte_get_hpet_hz() API calls,
These generic APIs can work with either TSC or HPET time sources, depending on what is requested by an application call to rte_eal_hpet_init(),
if any, and on what is available on the system at runtime.
-Running Intel® DPDK Applications Without Root Privileges
+Running DPDK Applications Without Root Privileges
--------------------------------------------------------
-Although applications using the Intel® DPDK use network ports and other hardware resources directly,
+Although applications using the DPDK use network ports and other hardware resources directly,
with a number of small permission adjustments it is possible to run these applications as a user other than “root”.
To do so, the ownership, or permissions, on the following Linux file system objects should be adjusted to ensure that
-the Linux user account being used to run the Intel® DPDK application has access to them:
+the Linux user account being used to run the DPDK application has access to them:
* All directories which serve as hugepage mount points, for example, /mnt/huge
* The userspace-io device files in /dev, for example, /dev/uio0, /dev/uio1, and so on
+* The userspace-io sysfs config and resource files, for example for uio0: /sys/class/uio/uio0/device/config /sys/class/uio/uio0/device/resource*
+
* If the HPET is to be used, /dev/hpet
.. note::
Power Management and Power Saving Functionality
-----------------------------------------------
-Enhanced Intel SpeedStep® Technology must be enabled in the platform BIOS if the power management feature of Intel® DPDK is to be used.
+Enhanced Intel SpeedStep® Technology must be enabled in the platform BIOS if the power management feature of DPDK is to be used.
Otherwise, the sys file folder /sys/devices/system/cpu/cpu0/cpufreq will not exist, and the CPU frequency- based power management cannot be used.
Consult the relevant BIOS documentation to determine how these settings can be accessed.
Using Linux* Core Isolation to Reduce Context Switches
------------------------------------------------------
-While the threads used by an Intel® DPDK application are pinned to logical cores on the system,
+While the threads used by an DPDK application are pinned to logical cores on the system,
it is possible for the Linux scheduler to run other tasks on those cores also.
To help prevent additional workloads from running on those cores,
it is possible to use the isolcpus Linux* kernel parameter to isolate them from the general Linux scheduler.
-For example, if Intel® DPDK applications are to run on logical cores 2, 4 and 6,
+For example, if DPDK applications are to run on logical cores 2, 4 and 6,
the following should be added to the kernel parameter list:
.. code-block:: console
isolcpus=2,4,6
-Loading the Intel® DPDK KNI Kernel Module
+Loading the DPDK KNI Kernel Module
-----------------------------------------
-To run the Intel® DPDK Kernel NIC Interface (KNI) sample application, an extra kernel module (the kni module) must be loaded into the running kernel.
-The module is found in the kmod sub-directory of the Intel® DPDK target directory.
+To run the DPDK Kernel NIC Interface (KNI) sample application, an extra kernel module (the kni module) must be loaded into the running kernel.
+The module is found in the kmod sub-directory of the DPDK target directory.
Similar to the loading of the igb_uio module, this module should be loaded using the insmod command as shown below
-(assuming that the current directory is the Intel® DPDK target directory):
+(assuming that the current directory is the DPDK target directory):
.. code-block:: console
.. note::
- See the “Kernel NIC Interface Sample Application” chapter in the *Intel® DPDK Sample Applications User Guide* for more details.
+ See the “Kernel NIC Interface Sample Application” chapter in the *DPDK Sample Applications User Guide* for more details.
-Using Linux IOMMU Pass-Through to Run Intel® DPDK with Intel® VT-d
-------------------------------------------------------------------
+Using Linux IOMMU Pass-Through to Run DPDK with Intel® VT-d
+-----------------------------------------------------------
To enable Intel® VT-d in a Linux kernel, a number of kernel configuration options must be set. These include:
* INTEL_IOMMU
-In addition, to run the Intel® DPDK with Intel® VT-d, the iommu=pt kernel parameter must be used when using igb_uio driver.
+In addition, to run the DPDK with Intel® VT-d, the iommu=pt kernel parameter must be used when using igb_uio driver.
This results in pass-through of the DMAR (DMA Remapping) lookup in the host.
Also, if INTEL_IOMMU_DEFAULT_ON is not set in the kernel, the intel_iommu=on kernel parameter must be used too.
This ensures that the Intel IOMMU is being initialized as expected.
High Performance of Small Packets on 40G NIC
--------------------------------------------
+As there might be firmware fixes for performance enhancement in latest version
+of firmware image, the firmware update might be needed for getting high performance.
+Check with the local Intel's Network Division application engineers for firmware updates.
+The base driver to support firmware version of FVL3E will be integrated in the next
+DPDK release, so currently the validated firmware version is 4.2.6.
+
Enabling Extended Tag and Setting Max Read Request Size
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
As i40e PMD supports both 16 and 32 bytes RX descriptor sizes, and 16 bytes size can provide helps to high performance of small packets.
Configuration of CONFIG_RTE_LIBRTE_I40E_16BYTE_RX_DESC in config files can be changed to use 16 bytes size RX descriptors.
+
+High Performance and per Packet Latency Tradeoff
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Due to the hardware design, the interrupt signal inside NIC is needed for per
+packet descriptor write-back. The minimum interval of interrupts could be set
+at compile time by CONFIG_RTE_LIBRTE_I40E_ITR_INTERVAL in configuration files.
+Though there is a default configuration, the interval could be tuned by the
+users with that configuration item depends on what the user cares about more,
+performance or per packet latency.
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