netdev - Re: [net-next PATCH 13/15] eth: fbnic: add basic Rx handling

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Message-ID: <9c19422a-942a-0178-8a0a-e30639ac038f@huawei.com>
Date: Fri, 12 Apr 2024 17:47:54 +0800
From: Yunsheng Lin <linyunsheng@...wei.com>
To: Alexander Duyck <alexander.duyck@...il.com>
CC: <netdev@...r.kernel.org>, Alexander Duyck <alexanderduyck@...com>,
	<kuba@...nel.org>, <davem@...emloft.net>, <pabeni@...hat.com>
Subject: Re: [net-next PATCH 13/15] eth: fbnic: add basic Rx handling

On 2024/4/12 16:43, Yunsheng Lin wrote:
> On 2024/4/10 23:03, Alexander Duyck wrote:

> 
> If we provide a proper frag API to reserve enough pagecnt_bias for caller to
> do its own fragmenting, then the memory waste may be avoided for this hw in
> system with PAGE_SIZE > 4K.
> 

Something like the page_pool_alloc_frag_bias() API below:

diff --git a/include/net/page_pool/helpers.h b/include/net/page_pool/helpers.h
index 1d397c1a0043..018943307e68 100644
--- a/include/net/page_pool/helpers.h
+++ b/include/net/page_pool/helpers.h
@@ -92,6 +92,14 @@ static inline struct page *page_pool_dev_alloc_pages(struct page_pool *pool)
        return page_pool_alloc_pages(pool, gfp);
 }

+static inline struct page *page_pool_alloc_frag(struct page_pool *pool,
+                                               unsigned int *offset,
+                                               unsigned int size,
+                                               gfp_t gfp)
+{
+       return page_pool_alloc_frag_bias(pool, offset, size, 1U, gfp);
+}
+
 /**
  * page_pool_dev_alloc_frag() - allocate a page fragment.
  * @pool: pool from which to allocate
diff --git a/include/net/page_pool/types.h b/include/net/page_pool/types.h
index 5e43a08d3231..2847b96264e5 100644
--- a/include/net/page_pool/types.h
+++ b/include/net/page_pool/types.h
@@ -202,8 +202,9 @@ struct page_pool {
 };

 struct page *page_pool_alloc_pages(struct page_pool *pool, gfp_t gfp);
-struct page *page_pool_alloc_frag(struct page_pool *pool, unsigned int *offset,
-                                 unsigned int size, gfp_t gfp);
+struct page *page_pool_alloc_frag_bias(struct page_pool *pool,
+                                      unsigned int *offset, unsigned int size,
+                                      unsigned int bias, gfp_t gfp);
 struct page_pool *page_pool_create(const struct page_pool_params *params);
 struct page_pool *page_pool_create_percpu(const struct page_pool_params *params,
                                          int cpuid);
diff --git a/net/core/page_pool.c b/net/core/page_pool.c
index 4c175091fc0a..441b54473c35 100644
--- a/net/core/page_pool.c
+++ b/net/core/page_pool.c
@@ -850,9 +850,11 @@ static void page_pool_free_frag(struct page_pool *pool)
        page_pool_return_page(pool, page);
 }

-struct page *page_pool_alloc_frag(struct page_pool *pool,
-                                 unsigned int *offset,
-                                 unsigned int size, gfp_t gfp)
+struct page *page_pool_alloc_frag_bias(struct page_pool *pool,
+                                      unsigned int *offset,
+                                      unsigned int size,
+                                      unsigned int bias,
+                                      gfp_t gfp)
 {
        unsigned int max_size = PAGE_SIZE << pool->p.order;
        struct page *page = pool->frag_page;
@@ -881,19 +883,19 @@ struct page *page_pool_alloc_frag(struct page_pool *pool,
                pool->frag_page = page;

 frag_reset:
-               pool->frag_users = 1;
+               pool->frag_users = bias;
                *offset = 0;
                pool->frag_offset = size;
                page_pool_fragment_page(page, BIAS_MAX);
                return page;
        }

-       pool->frag_users++;
+       pool->frag_users += bias;
        pool->frag_offset = *offset + size;
        alloc_stat_inc(pool, fast);
        return page;
 }
-EXPORT_SYMBOL(page_pool_alloc_frag);
+EXPORT_SYMBOL(page_pool_alloc_frag_bias);

 static void page_pool_empty_ring(struct page_pool *pool)
 {