Re: [PATCH RFC net-next 2/3] net: page_pool: use alloc_pages_bulk in refill code path
From: Jesper Dangaard Brouer
Date: Fri Feb 26 2021 - 09:34:25 EST
On 2021年2月24日 22:15:22 +0200
Ilias Apalodimas <ilias.apalodimas@xxxxxxxxxx> wrote:
>
Hi Jesper,
>
>
On Wed, Feb 24, 2021 at 07:56:46PM +0100, Jesper Dangaard Brouer wrote:
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> There are cases where the page_pool need to refill with pages from the
>
> page allocator. Some workloads cause the page_pool to release pages
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> instead of recycling these pages.
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>
>
> For these workload it can improve performance to bulk alloc pages from
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> the page-allocator to refill the alloc cache.
>
>
>
> For XDP-redirect workload with 100G mlx5 driver (that use page_pool)
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> redirecting xdp_frame packets into a veth, that does XDP_PASS to create
>
> an SKB from the xdp_frame, which then cannot return the page to the
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> page_pool. In this case, we saw[1] an improvement of 18.8% from using
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> the alloc_pages_bulk API (3,677,958 pps -> 4,368,926 pps).
>
>
>
> [1] https://github.com/xdp-project/xdp-project/blob/master/areas/mem/page_pool06_alloc_pages_bulk.org
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>
>
> Signed-off-by: Jesper Dangaard Brouer <brouer@xxxxxxxxxx>
>
>
[...]
>
>
> + /* Remaining pages store in alloc.cache */
>
> + list_for_each_entry_safe(page, next, &page_list, lru) {
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> + list_del(&page->lru);
>
> + if (pp_flags & PP_FLAG_DMA_MAP) {
>
> + page = page_pool_dma_map(pool, page);
>
> + if (!page)
>
>
As I commented on the previous patch, i'd prefer the put_page() here to be
>
explicitly called, instead of hiding in the page_pool_dma_map()
I fully agree. I will fixup the code.
>
> + continue;
>
> + }
>
> + if (likely(pool->alloc.count < PP_ALLOC_CACHE_SIZE)) {
>
> + pool->alloc.cache[pool->alloc.count++] = page;
>
> + pool->pages_state_hold_cnt++;
>
> + trace_page_pool_state_hold(pool, page,
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> + pool->pages_state_hold_cnt);
>
> + } else {
>
> + put_page(page);
>
> + }
>
> + }
>
> +out:
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> if (pool->p.flags & PP_FLAG_DMA_MAP) {
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> - page = page_pool_dma_map(pool, page);
>
> - if (!page)
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> + first_page = page_pool_dma_map(pool, first_page);
>
> + if (!first_page)
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> return NULL;
>
> }
>
>
>
[...]
--
Best regards,
Jesper Dangaard Brouer
MSc.CS, Principal Kernel Engineer at Red Hat
LinkedIn:
http://www.linkedin.com/in/brouer