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By using CQE based moderation on TX CQ we can reduce the number of TX interrupt rate. Besides the benefit of less interrupts, this also allows the kernel to better utilize TSO. Since TSO has some CPU overhead, it might not aggregate when CPU is under high stress. By reducing the interrupt rate and the CPU utilization, we can get better aggregation and better overall throughput. The feature is enabled by default and has a private flag in ethtool for control. Throughput, interrupt rate and TSO utilization improvements: (ConnectX-4Lx 40GbE, unidirectional, 1/16 TCP streams, 64B packets) --------------------------------------------------------- Metric | Streams | CQE Based | EQE Based | improvement --------------------------------------------------------- BW | 1 | 2.4Gb/s | 2.15Gb/s | +11.6% IR | 1 | 27Kips | 50.6Kips | -46.7% TSO Util | 1 | 74.6% | 71% | +5% BW | 16 | 29Gb/s | 25.85Gb/s | +12.2% IR | 16 | 482Kips | 745Kips | -35.3% TSO Util | 16 | 69.1% | 49% | +41.1% *BW = Bandwidth, IR = Interrupt rate, ips = interrupt per second. TSO Util = bytes in TSO sessions / all bytes transferred Signed-off-by: Tal Gilboa <talgi@mellanox.com> Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. 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.