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To avoid overflowing the page pool's cache, don't release the whole bulk which is usually larger than the cache refill size. Group release+alloc instead into cache refill units that allow releasing to the cache and then allocating from the cache. A refill_unit variable is added as a iteration unit over the wqe_bulk when doing release+alloc. For a single ring, single core, default MTU (1500) TCP stream test the number of pages allocated from the cache directly (rx_pp_recycle_cached) increases from 0% to 52%: +---------------------------------------------+ | Page Pool stats (/sec) | Before | After | +-------------------------+---------+---------+ |rx_pp_alloc_fast | 2145422 | 2193802 | |rx_pp_alloc_slow | 2 | 0 | |rx_pp_alloc_empty | 2 | 0 | |rx_pp_alloc_refill | 34059 | 16634 | |rx_pp_alloc_waive | 0 | 0 | |rx_pp_recycle_cached | 0 | 1145818 | |rx_pp_recycle_cache_full | 0 | 0 | |rx_pp_recycle_ring | 2179361 | 1064616 | |rx_pp_recycle_ring_full | 121 | 0 | +---------------------------------------------+ With this patch, the performance for legacy rq for the above test is back to baseline. Signed-off-by: Dragos Tatulea <dtatulea@nvidia.com> Signed-off-by: Saeed Mahameed <saeedm@nvidia.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.