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Existing MANA design assigns IRQ to every CPU, including sibling hyper-threads. This may cause multiple IRQs to be active simultaneously in the same core and may reduce the network performance. Improve the performance by assigning IRQ to non sibling CPUs in local NUMA node. The performance improvement we are getting using ntttcp with following patch is around 15 percent against existing design and approximately 11 percent, when trying to assign one IRQ in each core across NUMA nodes, if enough cores are present. The change will improve the performance for the system with high number of CPU, where number of CPUs in a node is more than 64 CPUs. Nodes with 64 CPUs or less than 64 CPUs will not be affected by this change. The performance study was done using ntttcp tool in Azure. The node had 2 nodes with 32 cores each, total 128 vCPU and number of channels were 32 for 32 RX rings. The below table shows a comparison between existing design and new design: IRQ node-num core-num CPU performance(%) 1 0 | 0 0 | 0 0 | 0-1 0 2 0 | 0 0 | 1 1 | 2-3 3 3 0 | 0 1 | 2 2 | 4-5 10 4 0 | 0 1 | 3 3 | 6-7 15 5 0 | 0 2 | 4 4 | 8-9 15 ... ... 25 0 | 0 12| 24 24| 48-49 12 ... 32 0 | 0 15| 31 31| 62-63 12 33 0 | 0 16| 0 32| 0-1 10 ... 64 0 | 0 31| 31 63| 62-63 0 Signed-off-by: Souradeep Chakrabarti <schakrabarti@linux.microsoft.com> Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.