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Commit 03e6d819 authored by Alexander Duyck's avatar Alexander Duyck Committed by David S. Miller
Browse files

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: default avatarAlexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: default avatarJeff Kirsher <jeffrey.t.kirsher@intel.com>
Acked-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: default avatarDavid 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;