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Commit 03c4cc38 authored by Jesper Dangaard Brouer's avatar Jesper Dangaard Brouer Committed by David S. Miller
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bpf: cpumap micro-optimization in cpu_map_enqueue 



Discovered that the compiler laid-out asm code in suboptimal way
when studying perf report during benchmarking of cpumap. Help
the compiler by the marking unlikely code paths.

Signed-off-by: default avatarJesper Dangaard Brouer <brouer@redhat.com>
Acked-by: default avatarJohn Fastabend <john.fastabend@gmail.com>
Acked-by: default avatarAlexei Starovoitov <ast@kernel.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 14e83bf8

kernel/bpf/cpumap.c

+2 −2
Original line number Diff line number Diff line
@@ -208,7 +208,7 @@ static struct xdp_pkt *convert_to_xdp_pkt(struct xdp_buff *xdp) 
	headroom = xdp->data - xdp->data_hard_start;

	metasize = xdp->data - xdp->data_meta;

	metasize = metasize > 0 ? metasize : 0;

	if ((headroom - metasize) < sizeof(*xdp_pkt))

	if (unlikely((headroom - metasize) < sizeof(*xdp_pkt)))

		return NULL;



	/* Store info in top of packet */
@@ -656,7 +656,7 @@ int cpu_map_enqueue(struct bpf_cpu_map_entry *rcpu, struct xdp_buff *xdp, 
	struct xdp_pkt *xdp_pkt;



	xdp_pkt = convert_to_xdp_pkt(xdp);

	if (!xdp_pkt)

	if (unlikely(!xdp_pkt))

		return -EOVERFLOW;



	/* Info needed when constructing SKB on remote CPU */