net_sched: sch_fq: change fq_flow size/layout (7ba0537c) · Commits · 戴 / test

sizeof(struct fq_flow) is 112 bytes on 64bit arches. This means that half of them use two cache lines, but 50% use three cache lines. This patch adds cache line alignment, and makes sure that only the first cache line is touched by fq_enqueue(), which is more expensive that fq_dequeue() in general. Signed-off-by:

Eric Dumazet <edumazet@google.com> Signed-off-by:

David S. Miller <davem@davemloft.net>

net/sched/sch_fq.c

+7 −2

Original line number	Diff line number	Diff line
		@@ -66,6 +66,7 @@ static inline struct fq_skb_cb fq_skb_cb(struct sk_buff skb)
		* in linear list (head,tail), otherwise are placed in a rbtree (t_root).
		*/
		struct fq_flow {
		/* First cache line : used in fq_gc(), fq_enqueue(), fq_dequeue() */
		struct rb_root t_root;
		struct sk_buff head; / list of skbs for this flow : first skb */
		union {
		@@ -74,14 +75,18 @@ struct fq_flow {
		};
		struct rb_node fq_node; /* anchor in fq_root[] trees */
		struct sock *sk;
		u32 socket_hash; /* sk_hash */
		int qlen; /* number of packets in flow queue */

		/* Second cache line, used in fq_dequeue() */
		int credit;
		u32 socket_hash; /* sk_hash */
		/* 32bit hole on 64bit arches */

		struct fq_flow next; / next pointer in RR lists */

		struct rb_node rate_node; /* anchor in q->delayed tree */
		u64 time_next_packet;
		};
		} ____cacheline_aligned_in_smp;

		struct fq_flow_head {
		struct fq_flow *first;

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