Commit 03e6d819 authored Mar 23, 2010 by Alexander Duyck Committed by David S. Miller Mar 24, 2010

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>

parent f6b9f4b2

include/linux/skbuff.h

+0 −6

Original line number	Diff line number	Diff line
		@@ -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;

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