From: Jesper Dangaard Brouer <brouer@redhat.com>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: David Miller <davem@davemloft.net>,
netdev <netdev@vger.kernel.org>, Amir Vadai <amirv@mellanox.com>,
John Fastabend <john.r.fastabend@intel.com>,
brouer@redhat.com
Subject: Re: [PATCH net-next] net: reorganize sk_buff for faster __copy_skb_header()
Date: Fri, 26 Sep 2014 10:35:32 +0200 [thread overview]
Message-ID: <20140926103532.52420a79@redhat.com> (raw)
In-Reply-To: <1411680004.16953.57.camel@edumazet-glaptop2.roam.corp.google.com>
On Thu, 25 Sep 2014 14:20:04 -0700
Eric Dumazet <eric.dumazet@gmail.com> wrote:
> From: Eric Dumazet <edumazet@google.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@google.com>
> ---
I'm impressed, network ninja!
Acked-by: Jesper Dangaard Brouer <brouer@redhat.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
next prev parent reply other threads:[~2014-09-26 8:35 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-25 14:17 [PATCH net-next] mlx4: exploit skb->xmit_more to conditionally send doorbell Eric Dumazet
2014-09-25 14:43 ` Jesper Dangaard Brouer
2014-09-25 15:06 ` Eric Dumazet
2014-09-25 15:36 ` Eric Dumazet
2014-09-25 15:40 ` Eric Dumazet
2014-09-25 16:19 ` Eric Dumazet
2014-09-25 20:47 ` Eric Dumazet
2014-09-25 20:58 ` Joe Perches
2014-09-25 21:20 ` [PATCH net-next] net: reorganize sk_buff for faster __copy_skb_header() Eric Dumazet
2014-09-26 8:35 ` Jesper Dangaard Brouer [this message]
2014-09-28 21:37 ` David Miller
2014-09-29 4:06 ` David Miller
2014-09-29 4:57 ` Eric Dumazet
2014-09-29 5:18 ` [PATCH v2 " Eric Dumazet
2014-09-29 16:27 ` David Miller
2014-09-25 15:53 ` [PATCH net-next] mlx4: exploit skb->xmit_more to conditionally send doorbell Alexei Starovoitov
2014-09-25 16:05 ` Eric Dumazet
2014-09-25 16:08 ` Alexei Starovoitov
2014-09-28 21:27 ` David Miller
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