On Wed, Jul 19, 2023 at 08:13:37PM +0800, Yunsheng Lin wrote:
Hi Yunsheng,
...
> diff --git a/include/net/page_pool_types.h b/include/net/page_pool_types.h
...
> +struct page_pool {
> + struct page_pool_params p;
> +
> + struct delayed_work release_dw;
> + void (*disconnect)(void *);
> + unsigned long defer_start;
> + unsigned long defer_warn;
> +
> + u32 pages_state_hold_cnt;
> + unsigned int frag_offset;
> + struct page *frag_page;
> + long frag_users;
> +
> +#ifdef CONFIG_PAGE_POOL_STATS
> + /* these stats are incremented while in softirq context */
> + struct page_pool_alloc_stats alloc_stats;
> +#endif
> + u32 xdp_mem_id;
> +
> + /*
> + * Data structure for allocation side
> + *
> + * Drivers allocation side usually already perform some kind
> + * of resource protection. Piggyback on this protection, and
> + * require driver to protect allocation side.
> + *
> + * For NIC drivers this means, allocate a page_pool per
> + * RX-queue. As the RX-queue is already protected by
> + * Softirq/BH scheduling and napi_schedule. NAPI schedule
> + * guarantee that a single napi_struct will only be scheduled
> + * on a single CPU (see napi_schedule).
> + */
> + struct pp_alloc_cache alloc ____cacheline_aligned_in_smp;
> +
> + /* Data structure for storing recycled pages.
> + *
> + * Returning/freeing pages is more complicated synchronization
> + * wise, because free's can happen on remote CPUs, with no
> + * association with allocation resource.
> + *
> + * Use ptr_ring, as it separates consumer and producer
> + * effeciently, it a way that doesn't bounce cache-lines.
I know this is moved from elsewhere, but: effeciently -> efficiently
> + *
> + * TODO: Implement bulk return pages into this structure.
> + */
> + struct ptr_ring ring;
> +
> +#ifdef CONFIG_PAGE_POOL_STATS
> + /* recycle stats are per-cpu to avoid locking */
> + struct page_pool_recycle_stats __percpu *recycle_stats;
> +#endif
> + atomic_t pages_state_release_cnt;
> +
> + /* A page_pool is strictly tied to a single RX-queue being
> + * protected by NAPI, due to above pp_alloc_cache. This
> + * refcnt serves purpose is to simplify drivers error handling.
> + */
> + refcount_t user_cnt;
> +
> + u64 destroy_cnt;
> +};
...
