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dd28d1a0b5
While doing stress tests with a disabled IP route cache, I found __mkroute_output() was touching three times in_device atomic refcount. Use RCU to touch it once to reduce cache line ping pongs. Before patch time to perform the test real 1m42.009s user 0m12.545s sys 25m0.726s Profile : 16109.00 26.4% ip_route_output_slow vmlinux 7434.00 12.2% dst_destroy vmlinux 3280.00 5.4% fib_rules_lookup vmlinux 3252.00 5.3% fib_semantic_match vmlinux 2622.00 4.3% fib_table_lookup vmlinux 2535.00 4.1% dst_alloc vmlinux 1750.00 2.9% _raw_read_lock vmlinux 1532.00 2.5% rt_set_nexthop vmlinux After patch real 1m36.503s user 0m12.977s sys 23m25.608s 14234.00 22.4% ip_route_output_slow vmlinux 8717.00 13.7% dst_destroy vmlinux 4052.00 6.4% fib_rules_lookup vmlinux 3951.00 6.2% fib_semantic_match vmlinux 3191.00 5.0% dst_alloc vmlinux 1764.00 2.8% fib_table_lookup vmlinux 1692.00 2.7% _raw_read_lock vmlinux 1605.00 2.5% rt_set_nexthop vmlinux Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>