>The mlx4 driver by default allocates order-3 pages for the ring to consume in >multiple fragments. When the device has an xdp program, this behavior will >prevent tx actions since the page must be re-mapped in TODEVICE mode, which >cannot be done if the page is still shared. > >Start by making the allocator configurable based on whether xdp is running, >such that order-0 pages are always used and never shared. > >Since this will stress the page allocator, add a simple page cache to each rx >ring. Pages in the cache are left dma-mapped, and in drop-only stress tests >the page allocator is eliminated from the perf report. > >Note that setting an xdp program will now require the rings to be reconfigured. > >Before: > 26.91% ksoftirqd/0 [mlx4_en] [k] mlx4_en_process_rx_cq > 17.88% ksoftirqd/0 [mlx4_en] [k] mlx4_en_alloc_frags > 6.00% ksoftirqd/0 [mlx4_en] [k] mlx4_en_free_frag > 4.49% ksoftirqd/0 [kernel.vmlinux] [k] get_page_from_freelist > 3.21% swapper [kernel.vmlinux] [k] intel_idle > 2.73% ksoftirqd/0 [kernel.vmlinux] [k] bpf_map_lookup_elem > 2.57% swapper [mlx4_en] [k] mlx4_en_process_rx_cq > >After: > 31.72% swapper [kernel.vmlinux] [k] intel_idle > 8.79% swapper [mlx4_en] [k] mlx4_en_process_rx_cq > 7.54% swapper [kernel.vmlinux] [k] poll_idle > 6.36% swapper [mlx4_core] [k] mlx4_eq_int > 4.21% swapper [kernel.vmlinux] [k] tasklet_action > 4.03% swapper [kernel.vmlinux] [k] cpuidle_enter_state > 3.43% swapper [mlx4_en] [k] mlx4_en_prepare_rx_desc > 2.18% swapper [kernel.vmlinux] [k] native_irq_return_iret > 1.37% swapper [kernel.vmlinux] [k] menu_select > 1.09% swapper [kernel.vmlinux] [k] bpf_map_lookup_elem > >Signed-off-by: Brenden Blanco <bbla...@plumgrid.com>
Reviewed-by: Tariq Toukan <tar...@mellanox.com>
