linux-kernel - [PATCH net-next] sock: make SKB_FRAG_PAGE_ORDER equal to PAGE_ALLOC_COSTLY

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Message-Id: <20241217105659.2215649-1-yajun.deng@linux.dev>
Date: Tue, 17 Dec 2024 18:56:59 +0800
From: Yajun Deng <yajun.deng@...ux.dev>
To: davem@...emloft.net,
	edumazet@...gle.com,
	kuba@...nel.org,
	pabeni@...hat.com,
	horms@...nel.org
Cc: netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Yajun Deng <yajun.deng@...ux.dev>
Subject: [PATCH net-next] sock: make SKB_FRAG_PAGE_ORDER equal to PAGE_ALLOC_COSTLY_ORDER

The SKB_FRAG_PAGE_ORDER will be 3 if PAGE_SIZE is 4096, and less than 3
if it is not. So it will increase the number of memory allocations if
PAGE_SIZE is greater than 4096.

alloc_pages() only relates to the order, if an order is less than or equal
to PAGE_ALLOC_COSTLY_ORDER, it will get the page from rmqueue_pcplist() in
rmqueue(). So there's no need for the order to be less than
PAGE_ALLOC_COSTLY_ORDER.

To decrease the number of memory allocations, make SKB_FRAG_PAGE_ORDER
equal to PAGE_ALLOC_COSTLY_ORDER even if PAGE_SIZE isn't 4096.

Signed-off-by: Yajun Deng <yajun.deng@...ux.dev>
---
 include/net/sock.h | 2 +-
 net/core/sock.c    | 3 +--
 2 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/include/net/sock.h b/include/net/sock.h
index 7464e9f9f47c..a33645226577 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -2853,7 +2853,7 @@ extern __u32 sysctl_rmem_max;
 extern __u32 sysctl_wmem_default;
 extern __u32 sysctl_rmem_default;
 
-#define SKB_FRAG_PAGE_ORDER	get_order(32768)
+#define SKB_FRAG_PAGE_ORDER	PAGE_ALLOC_COSTLY_ORDER
 DECLARE_STATIC_KEY_FALSE(net_high_order_alloc_disable_key);
 
 static inline int sk_get_wmem0(const struct sock *sk, const struct proto *proto)
diff --git a/net/core/sock.c b/net/core/sock.c
index 74729d20cd00..0db306f4216c 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -3014,8 +3014,7 @@ bool skb_page_frag_refill(unsigned int sz, struct page_frag *pfrag, gfp_t gfp)
 	}
 
 	pfrag->offset = 0;
-	if (SKB_FRAG_PAGE_ORDER &&
-	    !static_branch_unlikely(&net_high_order_alloc_disable_key)) {
+	if (!static_branch_unlikely(&net_high_order_alloc_disable_key)) {
 		/* Avoid direct reclaim but allow kswapd to wake */
 		pfrag->page = alloc_pages((gfp & ~__GFP_DIRECT_RECLAIM) |
 					  __GFP_COMP | __GFP_NOWARN |
-- 
2.25.1