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  1. Apr 13, 2017
    • Alexey Dobriyan's avatar
      net: make struct net_device::min_header_len 8-bit · d92be7a4
      Alexey Dobriyan authored 
      

This field is never big enough to warrant 16-bitness.

8-bit accesses enjoy shorted encoding on i386/x86_64 than 16-bit
accesses:

	add/remove: 0/0 grow/shrink: 0/2 up/down: 0/-10 (-10)
	function                                     old     new   delta
	loopback_setup                               169     164      -5
	ether_setup                                  148     143      -5

Signed-off-by: default avatarAlexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      d92be7a4
    • Alexey Dobriyan's avatar
      net: neigh: make ->hh_len 32-bit · 5b3dc2f3
      Alexey Dobriyan authored 
      

Using 16-bit ->hh_len doesn't save any memory, save some .text instead:

	add/remove: 0/0 grow/shrink: 1/6 up/down: 2/-19 (-17)
	function                                     old     new   delta
	neigh_update                                2312    2314      +2
	fwnet_header_cache                           199     197      -2
	eth_header_cache                             101      99      -2
	ip6_finish_output2                          2371    2368      -3
	vrf_finish_output6                          1522    1518      -4
	vrf_finish_output                           1413    1409      -4
	ip_finish_output2                           1627    1623      -4

Signed-off-by: default avatarAlexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      5b3dc2f3
    • Ilan Tayari's avatar
      gso: Support frag_list splitting with head_frag · eaffadbb
      Ilan Tayari authored 
      A driver may use build_skb() for received packets.
These SKBs then have a head_frag.

Since commit d7e8883c ("net: make GRO aware of
skb->head_frag"), GRO may build frag_list SKBs out of
head_frag received SKBs.
In such a case, the chained SKBs end up with a head_frag.

Commit 07b26c94

 ("gso: Support partial splitting at
the frag_list pointer") adds partial segmentation of frag_list
SKB chains into individual SKBs.
However, this is not done if the chained SKBs have any
linear part, because the device may not be able to DMA
the private linear buffer.

A chained frag_list SKB with head_frag is wrongfully
detected in this case as having a private linear part
and thus falls back to software GSO, while in fact the
linear part is backed by a DMA page just like any other frag.

This causes low performance when forwarding those packets
that were built with build_skb()

Allow partial segmentation at the frag_list pointer for
chained SKBs with head_frag.

Note that such SKBs can only be created by GRO, when applied
to received packets with head_frag.
Also note that this change only affects the data path that
performs the partial segmentation at frag_list pointer, and
not any of the other more common data paths.

Signed-off-by: default avatarIlan Tayari <ilant@mellanox.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      eaffadbb
  3. Apr 12, 2017