|
|
|
|
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
|
|
|
|
|
@@ -2067,6 +2067,24 @@ 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
|
