On Fri, Aug 14, 2009 at 02:10:45PM -0700, Linus Torvalds wrote:
> On Fri, 14 Aug 2009, Linus Torvalds wrote:
> >
> > But not inline in the code, though. So yeah, it has a memory footprint,
> > but shouldn't have a cache footprint.
>
> An example of this: stack usage. This is the code with BUG_ON():
>
> skb_push:
> push %rbp
> mov %esi,%eax
> add %esi,0x68(%rdi)
> neg %rax
> mov %rsp,%rbp
> add 0xd8(%rdi),%rax
> mov %rax,0xd8(%rdi)
> cmp 0xd0(%rdi),%rax
> jae 2f
> ud2a
> 1: jmp 1b
> 2: leaveq
> retq
An allyesconfig (CONFIG_FTRACE disabled) on x86_64 with gcc 4.3.2 results in
the following vmlinux sizes:
574152755 2009-08-16 20:05 vmlinux-orig
574862000 2009-08-16 20:13 vmlinux-skb-inline
The skb-inline variant was created by using your patch and on top of it the
patch below. Size increased by 692KB (0.12%).
Dunno.. is that acceptable?
---
include/linux/skbuff.h | 35 +++++++++++++++++++++++++++++++++--
net/core/skbuff.c | 38 --------------------------------------
2 files changed, 33 insertions(+), 40 deletions(-)
Index: linux-2.6/include/linux/skbuff.h
===================================================================
--- linux-2.6.orig/include/linux/skbuff.h
+++ linux-2.6/include/linux/skbuff.h
@@ -1116,7 +1116,6 @@ static inline void skb_set_tail_pointer(
/*
* Add data to an sk_buff
*/
-extern unsigned char *skb_put(struct sk_buff *skb, unsigned int len);
static inline unsigned char *__skb_put(struct sk_buff *skb, unsigned int len)
{
unsigned char *tmp = skb_tail_pointer(skb);
@@ -1126,7 +1125,23 @@ static inline unsigned char *__skb_put(s
return tmp;
}
-extern unsigned char *skb_push(struct sk_buff *skb, unsigned int len);
+/**
+ * skb_put - add data to a buffer
+ * @skb: buffer to use
+ * @len: amount of data to add
+ *
+ * This function extends the used data area of the buffer. If this would
+ * exceed the total buffer size the kernel will panic. A pointer to the
+ * first byte of the extra data is returned.
+ */
+static inline unsigned char *skb_put(struct sk_buff *skb, unsigned int len)
+{
+ unsigned char *tmp = __skb_put(skb, len);
+
+ BUG_ON(skb->tail > skb->end);
+ return tmp;
+}
+
static inline unsigned char *__skb_push(struct sk_buff *skb, unsigned int len)
{
skb->data -= len;
@@ -1134,6 +1149,22 @@ static inline unsigned char *__skb_push(
return skb->data;
}
+/**
+ * skb_push - add data to the start of a buffer
+ * @skb: buffer to use
+ * @len: amount of data to add
+ *
+ * This function extends the used data area of the buffer at the buffer
+ * start. If this would exceed the total buffer headroom the kernel will
+ * panic. A pointer to the first byte of the extra data is returned.
+ */
+static inline unsigned char *skb_push(struct sk_buff *skb, unsigned int len)
+{
+ __skb_push(skb, len);
+ BUG_ON(skb->data < skb->head);
+ return skb->data;
+}
+
extern unsigned char *skb_pull(struct sk_buff *skb, unsigned int len);
static inline unsigned char *__skb_pull(struct sk_buff *skb, unsigned int len)
{
Index: linux-2.6/net/core/skbuff.c
===================================================================
--- linux-2.6.orig/net/core/skbuff.c
+++ linux-2.6/net/core/skbuff.c
@@ -955,44 +955,6 @@ free_skb:
EXPORT_SYMBOL(skb_pad);
/**
- * skb_put - add data to a buffer
- * @skb: buffer to use
- * @len: amount of data to add
- *
- * This function extends the used data area of the buffer. If this would
- * exceed the total buffer size the kernel will panic. A pointer to the
- * first byte of the extra data is returned.
- */
-unsigned char *skb_put(struct sk_buff *skb, unsigned int len)
-{
- unsigned char *tmp = skb_tail_pointer(skb);
- SKB_LINEAR_ASSERT(skb);
- skb->tail += len;
- skb->len += len;
- BUG_ON(skb->tail > skb->end);
- return tmp;
-}
-EXPORT_SYMBOL(skb_put);
-
-/**
- * skb_push - add data to the start of a buffer
- * @skb: buffer to use
- * @len: amount of data to add
- *
- * This function extends the used data area of the buffer at the buffer
- * start. If this would exceed the total buffer headroom the kernel will
- * panic. A pointer to the first byte of the extra data is returned.
- */
-unsigned char *skb_push(struct sk_buff *skb, unsigned int len)
-{
- skb->data -= len;
- skb->len += len;
- BUG_ON(skb->data < skb->head);
- return skb->data;
-}
-EXPORT_SYMBOL(skb_push);
-
-/**
* skb_pull - remove data from the start of a buffer
* @skb: buffer to use
* @len: amount of data to remove
--
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