d034d02de8
When constructing a heap, heapify operations are required on all non-leaf nodes. Thus, determining the index of the first non-leaf node is crucial. In a heap, the left child's index of node i is 2 * i + 1 and the right child's index is 2 * i + 2. Node CAKE_MAX_TINS * CAKE_QUEUES / 2 has its left and right children at indexes CAKE_MAX_TINS * CAKE_QUEUES + 1 and CAKE_MAX_TINS * CAKE_QUEUES + 2, respectively, which are beyond the heap's range, indicating it as a leaf node. Conversely, node CAKE_MAX_TINS * CAKE_QUEUES / 2 - 1 has a left child at index CAKE_MAX_TINS * CAKE_QUEUES - 1, confirming its non-leaf status. The loop should start from it since it's not a leaf node. By starting the loop from CAKE_MAX_TINS * CAKE_QUEUES / 2 - 1, we minimize function calls and branch condition evaluations. This adjustment theoretically reduces two function calls (one for cake_heapify() and another for cake_heap_get_backlog()) and five branch evaluations (one for iterating all non-leaf nodes, one within cake_heapify()'s while loop, and three more within the while loop with if conditions). Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com> Acked-by: Toke Høiland-Jørgensen <toke@toke.dk> Link: https://lore.kernel.org/r/20240408174716.751069-1-visitorckw@gmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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 reStructuredText 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.