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- From 4593a806e31119c5bd3faa00c7210ad862d515af Mon Sep 17 00:00:00 2001
- From: Dave Taht <dave.taht@bufferbloat.net>
- Date: Mon, 31 Dec 2012 10:02:21 -0800
- Subject: [PATCH 3/7] skb_reduce_truesize: helper function for shrinking skbs
- whenever needed
- On embedded devices in particular, large queues of small packets from the rx
- path with a large truesize can exist. Reducing their size can reduce
- memory pressure. skb_reduce_truesize is a helper function for doing this,
- when needed.
- ---
- include/linux/skbuff.h | 18 ++++++++++++++++++
- 1 file changed, 18 insertions(+)
- --- a/include/linux/skbuff.h
- +++ b/include/linux/skbuff.h
- @@ -2097,6 +2097,24 @@ static inline void pskb_trim_unique(stru
- BUG_ON(err);
- }
-
- +/*
- + * Caller wants to reduce memory needs before queueing skb
- + * The (expensive) copy should not be be done in fast path.
- + */
- +static inline struct sk_buff *skb_reduce_truesize(struct sk_buff *skb)
- +{
- + if (skb->truesize > 2 * SKB_TRUESIZE(skb->len)) {
- + struct sk_buff *nskb;
- + nskb = skb_copy_expand(skb, skb_headroom(skb), 0,
- + GFP_ATOMIC | __GFP_NOWARN);
- + if (nskb) {
- + __kfree_skb(skb);
- + skb = nskb;
- + }
- + }
- + return skb;
- +}
- +
- /**
- * skb_orphan - orphan a buffer
- * @skb: buffer to orphan
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