From: Jesper Dangaard Brouer <bro...@redhat.com> Date: Mon, 28 Sep 2015 12:47:14 +0200
> Noticed that the compiler (gcc version 4.8.5 20150623 (Red Hat 4.8.5-4) (GCC)) > generated suboptimal assembler code in eth_get_headlen(). > > This early return coding style is usually not an issue, on super scalar CPUs, > but the compiler choose to put the return statement after this very unlikely > branch, thus creating larger jump down to the likely code path. > > Performance wise, I could measure slightly less L1-icache-load-misses > and less branch-misses, and an improvement of 1 nanosec with an IP-forwarding > use-case with 257 bytes packets with ixgbe (CPU i7-4790K @ 4.00GHz). > > Signed-off-by: Jesper Dangaard Brouer <bro...@redhat.com> Applied, thanks Jesper. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
