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skbuff: remove unused dma_head & dma_maps fields 

The dma map fields in the skb_shared_info structure no longer has any users
and can be dropped since it is making the skb_shared_info unecessarily larger.

Running slabtop show that we were using 4K slabs for the skb->head on x86_64 w/
an allocation size of 1522.  It turns out that the dma_head and dma_maps array
made skb_shared large enough that we had crossed over the 2k boundary with
standard frames and as such we were using 4k blocks of memory for all skbs.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Alexander Duyck 2010-03-23 20:40:50 +00:00 committed by David S. Miller
parent f6b9f4b263
commit 03e6d819c2
1 changed files with 0 additions and 6 deletions
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6
include/linux/skbuff.h
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@ -190,9 +190,6 @@ struct skb_shared_info {
atomic_t dataref;
unsigned short nr_frags;
unsigned short gso_size;
#ifdef CONFIG_HAS_DMA
dma_addr_t dma_head;
#endif
/* Warning: this field is not always filled in (UFO)! */
unsigned short gso_segs;
unsigned short gso_type;
@ -201,9 +198,6 @@ struct skb_shared_info {
struct sk_buff *frag_list;
struct skb_shared_hwtstamps hwtstamps;
skb_frag_t frags[MAX_SKB_FRAGS];
#ifdef CONFIG_HAS_DMA
dma_addr_t dma_maps[MAX_SKB_FRAGS];
#endif
/* Intermediate layers must ensure that destructor_arg
* remains valid until skb destructor */
void * destructor_arg;