diff options
Diffstat (limited to 'doc/guides/linux_gsg/enable_func.rst')
| -rw-r--r-- | doc/guides/linux_gsg/enable_func.rst | 37 |
1 files changed, 10 insertions, 27 deletions
diff --git a/doc/guides/linux_gsg/enable_func.rst b/doc/guides/linux_gsg/enable_func.rst index 04e066c9..5ac0184a 100644 --- a/doc/guides/linux_gsg/enable_func.rst +++ b/doc/guides/linux_gsg/enable_func.rst @@ -35,8 +35,8 @@ Enabling Additional Functionality .. _High_Precision_Event_Timer: -High Precision Event Timer HPET) Functionality ----------------------------------------------- +High Precision Event Timer (HPET) Functionality +----------------------------------------------- BIOS Support ~~~~~~~~~~~~ @@ -87,6 +87,14 @@ The application can then determine what action to take, if any, if the HPET is n Running DPDK Applications Without Root Privileges -------------------------------------------------------- +.. note:: + + The instructions below will allow running DPDK as non-root with older + Linux kernel versions. However, since version 4.0, the kernel does not allow + unprivileged processes to read the physical address information from + the pagemaps file, making it impossible for those processes to use HW + devices which require physical addresses + 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 @@ -176,28 +184,3 @@ Also, if ``INTEL_IOMMU_DEFAULT_ON`` is not set in the kernel, the ``intel_iommu= This ensures that the Intel IOMMU is being initialized as expected. Please note that while using ``iommu=pt`` is compulsory for ``igb_uio driver``, the ``vfio-pci`` driver can actually work with both ``iommu=pt`` and ``iommu=on``. - -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. -Users should consult the release notes specific to a DPDK release to identify -the validated firmware version for a NIC using the i40e driver. - -Use 16 Bytes RX Descriptor 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. |