New upstream version 17.08

[deb_dpdk.git] / doc / guides / linux_gsg / enable_func.rst

diff --git a/doc/guides/linux_gsg/enable_func.rst b/doc/guides/linux_gsg/enable_func.rst
index 04e066c..5ac0184 100644 (file)
--- 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.