5ffb4d858b
Currently, different formulas are used to estimate the space that may be taken by WQEs in the SQ during a single packet transmit. This space is called stop room, and it's checked in the end of packet transmit to find out if the next packet could overflow the SQ. If it could, the driver tells the kernel to stop sending next packets. Many factors affect the stop room: 1. Padding with NOPs to avoid WQEs spanning over page boundaries. 2. Enabled and disabled offloads (TLS, upcoming MPWQE). 3. The maximum size of a WQE. The padding is performed before every WQE if it doesn't fit the current page. The current formula assumes that only one padding will be required per packet, and it doesn't take into account that the WQEs posted during the transmission of a single packet might exceed the page size in very rare circumstances. For example, to hit this condition with 4096-byte pages, TLS offload will have to interrupt an almost-full MPWQE session, be in the resync flow and try to transmit a near to maximum amount of data. To avoid SQ overflows in such rare cases after MPWQE is added, this patch introduces a more robust formula to estimate the stop room. The new formula uses the fact that a WQE of size X will not require more than X-1 WQEBBs of padding. More exact estimations are possible, but they result in much more complex and error-prone code for little gain. Before this patch, the TLS stop room included space for both INNOVA and ConnectX TLS offloads that couldn't run at the same time anyway, so this patch accounts only for the active one. Signed-off-by: Maxim Mikityanskiy <maximmi@mellanox.com> Reviewed-by: Tariq Toukan <tariqt@mellanox.com> Signed-off-by: Saeed Mahameed <saeedm@mellanox.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.