netdev - [PATCH net-next 02/15] net: page_pool: avoid touching slow on the fastpath

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Date: Tue, 24 Oct 2023 09:02:07 -0700
From: Jakub Kicinski <kuba@...nel.org>
To: davem@...emloft.net
Cc: netdev@...r.kernel.org,
	edumazet@...gle.com,
	pabeni@...hat.com,
	almasrymina@...gle.com,
	hawk@...nel.org,
	ilias.apalodimas@...aro.org,
	Jakub Kicinski <kuba@...nel.org>
Subject: [PATCH net-next 02/15] net: page_pool: avoid touching slow on the fastpath

To fully benefit from previous commit add one byte of state
in the first cache line recording if we need to look at
the slow part.

The packing isn't all that impressive right now, we create
a 7B hole. I'm expecting Olek's rework will reshuffle this,
anyway.

Acked-by: Jesper Dangaard Brouer <hawk@...nel.org>
Acked-by: Ilias Apalodimas <ilias.apalodimas@...aro.org>
Reviewed-by: Mina Almasry <almasrymina@...gle.com>
Signed-off-by: Jakub Kicinski <kuba@...nel.org>
---
 include/net/page_pool/types.h | 2 ++
 net/core/page_pool.c          | 4 +++-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/include/net/page_pool/types.h b/include/net/page_pool/types.h
index 23950fcc4eca..e1bb92c192de 100644
--- a/include/net/page_pool/types.h
+++ b/include/net/page_pool/types.h
@@ -125,6 +125,8 @@ struct page_pool_stats {
 struct page_pool {
 	struct page_pool_params_fast p;
 
+	bool has_init_callback;
+
 	long frag_users;
 	struct page *frag_page;
 	unsigned int frag_offset;
diff --git a/net/core/page_pool.c b/net/core/page_pool.c
index 5cae413de7cc..08af9de8e8eb 100644
--- a/net/core/page_pool.c
+++ b/net/core/page_pool.c
@@ -212,6 +212,8 @@ static int page_pool_init(struct page_pool *pool,
 		 */
 	}
 
+	pool->has_init_callback = !!pool->slow.init_callback;
+
 #ifdef CONFIG_PAGE_POOL_STATS
 	pool->recycle_stats = alloc_percpu(struct page_pool_recycle_stats);
 	if (!pool->recycle_stats)
@@ -385,7 +387,7 @@ static void page_pool_set_pp_info(struct page_pool *pool,
 	 * the overhead is negligible.
 	 */
 	page_pool_fragment_page(page, 1);
-	if (pool->slow.init_callback)
+	if (pool->has_init_callback)
 		pool->slow.init_callback(page, pool->slow.init_arg);
 }
 
-- 
2.41.0