4c2a132368
Currently, for striding RQ, fragmented pages from the page pool can get released in two ways: 1) In the mlx5e driver when trimming off the unused fragments AND the associated skb fragments have been released. This path allows recycling of pages to the page pool cache (allow_direct == true). 2) On the skb release path (last fragment release), which will always release pages to the page pool ring (allow_direct == false). Whichever is releasing the last fragment will be decisive on where the page gets released: the cache or the ring. So we obviously want to maximize for doing the release from 1. This patch does that by deferring the release of page fragments right before requesting new ones from the page pool. Extra care needs to be taken for the corner cases: * On first call, make sure that release is not called. The skip_release_bitmap is used for this purpose. * On rq shutdown, make sure that all wqes that were not in the linked list are released. 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 31 % to 98 %: +----------------------------------------------+ | Page Pool stats (/sec) | Before | After | +-------------------------+---------+----------+ |rx_pp_alloc_fast | 2137754 | 2261033 | |rx_pp_alloc_slow | 47 | 9 | |rx_pp_alloc_empty | 47 | 9 | |rx_pp_alloc_refill | 23230 | 819 | |rx_pp_alloc_waive | 0 | 0 | |rx_pp_recycle_cached | 672182 | 2209015 | |rx_pp_recycle_cache_full | 1789 | 0 | |rx_pp_recycle_ring | 1485848 | 52259 | |rx_pp_recycle_ring_full | 3003 | 584 | +----------------------------------------------+ With this patch, the performance in striding rq for the above test is back to baseline. Signed-off-by: Dragos Tatulea <dtatulea@nvidia.com> Reviewed-by: Tariq Toukan <tariqt@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.