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From: Alexey Dobriyan <adobriyan@gmail.com>
To: steffen.klassert@secunet.com
Cc: edumazet@google.com, davem@davemloft.net, netdev@vger.kernel.org
Subject: Re: [PATCH net-next 0/1 v2] skbuff: Extend gso_type to unsigned int.
Date: Sun, 9 Apr 2017 19:07:24 +0300	[thread overview]
Message-ID: <20170409160724.GA28980@avx2> (raw)

>  struct skb_shared_info {
> +	unsigned short	_unused;
>  	unsigned char	nr_frags;

This makes _all_ fields to be accessed with offset, but if you move
padding down, at least ->nr_frags will enjoy clean and simple [R64]
addressing.

On allyesconfig-ish kernel:

	before:	+542 = 720-178
	 after:	-158 =  53-211 (negative, because 16-bit field became 32-bit)

You may want to add configurable redzone there instead of padding
if that what you want. 2 bytes is nothing.

             reply	other threads:[~2017-04-09 16:07 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-04-09 16:07 Alexey Dobriyan [this message]
  -- strict thread matches above, loose matches on Subject: below --
2017-04-08 18:36 [PATCH net-next 0/1 v2] skbuff: Extend gso_type to unsigned int Steffen Klassert
2017-04-08 18:36 ` Steffen Klassert
2017-04-08 18:55   ` Eric Dumazet
2017-04-08 19:32     ` David Miller

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