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From: Roland Dreier <rdreier@cisco.com>
To: Stephen Hemminger <shemminger@linux-foundation.org>
Cc: David Miller <davem@davemloft.net>, netdev@vger.kernel.org
Subject: Re: [RFC 2/2] shrink size of scatterlist on common i386/x86-64
Date: Thu, 05 Jul 2007 16:32:45 -0700	[thread overview]
Message-ID: <adak5te2zqa.fsf@cisco.com> (raw)
In-Reply-To: <20070705231615.451797310@linux-foundation.org> (Stephen Hemminger's message of "Thu, 05 Jul 2007 16:14:14 -0700")

 > --- a/include/asm-i386/scatterlist.h	2007-07-05 14:37:11.000000000 -0700
 > +++ b/include/asm-i386/scatterlist.h	2007-07-05 15:44:51.000000000 -0700
 > @@ -5,9 +5,9 @@
 >  
 >  struct scatterlist {
 >      struct page		*page;
 > -    unsigned int	offset;
 >      dma_addr_t		dma_address;
 > -    unsigned int	length;
 > +    u16			offset;
 > +    u16			length;
 >  };

Actually this struct layout could be even better, since pointers are
32 bits but dma_addr_t may be 64 bits... having

struct scatterlist {
	dma_addr_t	dma_address;
	struct page    *page;
	u16		offset;
	u16		length;
};

would allow struct scatterlist to be 16 bytes.  Seems like a good thing...

 - R.

  reply	other threads:[~2007-07-05 23:32 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-07-05 23:14 [RFC 0/2] Convert skb to use scatterlist Stephen Hemminger
2007-07-05 23:14 ` [RFC 1/2] skbuff: " Stephen Hemminger
2007-07-05 23:14 ` [RFC 2/2] shrink size of scatterlist on common i386/x86-64 Stephen Hemminger
2007-07-05 23:32   ` Roland Dreier [this message]
2007-07-05 23:43   ` David Miller
2007-07-06  0:00     ` Stephen Hemminger
2007-07-06  0:15       ` David Miller
2007-07-06  7:43         ` Rusty Russell
2007-07-06  8:54           ` David Miller
2007-07-06 17:14         ` Williams, Mitch A
2007-07-06 19:20           ` David Miller
2007-07-08 16:17             ` Muli Ben-Yehuda
2007-07-09  7:06               ` David Miller
2007-07-09  8:53                 ` Muli Ben-Yehuda
2007-07-08 16:11           ` Muli Ben-Yehuda
2007-07-11 23:46             ` Williams, Mitch A

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