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Date: Fri, 26 Sep 2014 10:35:32 +0200 From: Jesper Dangaard Brouer <brouer@...hat.com> To: Eric Dumazet <eric.dumazet@...il.com> Cc: David Miller <davem@...emloft.net>, netdev <netdev@...r.kernel.org>, Amir Vadai <amirv@...lanox.com>, John Fastabend <john.r.fastabend@...el.com>, brouer@...hat.com Subject: Re: [PATCH net-next] net: reorganize sk_buff for faster __copy_skb_header() On Thu, 25 Sep 2014 14:20:04 -0700 Eric Dumazet <eric.dumazet@...il.com> wrote: > From: Eric Dumazet <edumazet@...gle.com> > > With proliferation of bit fields in sk_buff, __copy_skb_header() became > quite expensive, showing as the most expensive function in a GSO > workload. > > __copy_skb_header() performance is also critical for non GSO TCP > operations, as it is used from skb_clone() > > This patch carefully moves all the fields that were not copied in a > separate zone : cloned, nohdr, fclone, peeked, head_frag, xmit_more > > Then I moved all other fields and all other copied fields in a section > delimited by headers_start[0]/headers_end[0] section so that we > can use a single memcpy() call, inlined by compiler using long > word load/stores. > > I also tried to make all copies in the natural orders of sk_buff, > to help hardware prefetching. > > I made sure sk_buff size did not change. > > Signed-off-by: Eric Dumazet <edumazet@...gle.com> > --- I'm impressed, network ninja! Acked-by: Jesper Dangaard Brouer <brouer@...hat.com> It would have been nice if you would have included the performance improvement you saw, e.g. from: http://thread.gmane.org/gmane.linux.network/332035/focus=332086 -- Best regards, Jesper Dangaard Brouer MSc.CS, Sr. Network Kernel Developer at Red Hat Author of http://www.iptv-analyzer.org LinkedIn: http://www.linkedin.com/in/brouer -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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