On Mon, Aug 17, 2009 at 11:26:29PM +0200, Ingo Molnar wrote:
> * Heiko Carstens <heiko.carstens@xxxxxxxxxx> wrote:
>
> > 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?
>
> i ported your patch to latest mainline (see it attached below) i've
> done x86(-64) defconfig (with disabled CONFIG_OPTIMIZE_INLINING)
> measurements vmlinux:
> +static inline unsigned char *skb_put(struct sk_buff *skb, unsigned int len)
> +{
> + unsigned char *tmp = __skb_put(skb, len);
> +
> + if (unlikely(skb->tail > skb->end))
> + skb_over_panic(skb, len, __builtin_return_address(0));
> + return tmp;
> +}
No, the proposed patch replaces skb_over_panic() with BUG_ON() (see below).
With that I get slightly different results. However that's on my Thinkpad
booted with maxcpus=1 and a 32 bit kernel. Kernel is latest git as of today.
Now, this is a completely different machine than yours. With a different
config, so the machine actually boots. But the numbers are strange.
Part of /proc/cpuinfo :
model name : Intel(R) Core(TM)2 CPU T7600 @ 2.33GHz
stepping : 6
cache size : 4096 KB
Without the patch the result is:
TCP latency using localhost: 0.2576 microseconds
TCP latency using localhost: 0.2571 microseconds
TCP latency using localhost: 0.2579 microseconds
TCP latency using localhost: 0.2573 microseconds
TCP latency using localhost: 0.2574 microseconds
TCP latency using localhost: 0.2583 microseconds
TCP latency using localhost: 0.2572 microseconds
TCP latency using localhost: 0.2582 microseconds
TCP latency using localhost: 0.2583 microseconds
TCP latency using localhost: 0.2584 microseconds
Performance counter stats for './lat_tcp localhost' (10 runs):
24578.750193 task-clock-msecs # 0.994 CPUs ( +- 0.295% )
57166815217 cycles # 2325.863 M/sec ( +- 0.296% )
24994309721 instructions # 0.437 IPC ( +- 0.288% )
53691289530 L1-icache-loads # 2184.460 M/sec ( +- 0.304% )
424027 L1-icache-load-misses # 0.017 M/sec ( +- 0.824% )
24.714691813 seconds time elapsed ( +- 0.285% )
With the patch I get this:
TCP latency using localhost: 0.2588 microseconds
TCP latency using localhost: 0.2589 microseconds
TCP latency using localhost: 0.2581 microseconds
TCP latency using localhost: 0.2586 microseconds
TCP latency using localhost: 0.2584 microseconds
TCP latency using localhost: 0.2588 microseconds
TCP latency using localhost: 0.2586 microseconds
TCP latency using localhost: 0.2589 microseconds
TCP latency using localhost: 0.2582 microseconds
TCP latency using localhost: 0.2586 microseconds
Performance counter stats for './lat_tcp localhost' (10 runs):
24464.554706 task-clock-msecs # 0.995 CPUs ( +- 0.063% )
56903708182 cycles # 2325.965 M/sec ( +- 0.063% )
24831456567 instructions # 0.436 IPC ( +- 0.048% )
53068943303 L1-icache-loads # 2169.218 M/sec ( +- 0.081% )
418802 L1-icache-load-misses # 0.017 M/sec ( +- 0.637% )
24.596311828 seconds time elapsed ( +- 0.097% )
So latency increases while all other numbers decrease..
---
include/linux/skbuff.h | 39 +++++++++++++++++++---
net/core/skbuff.c | 85 -------------------------------------------------
2 files changed, 33 insertions(+), 91 deletions(-)
Index: linux-2.6/include/linux/skbuff.h
===================================================================
--- linux-2.6.orig/include/linux/skbuff.h
+++ linux-2.6/include/linux/skbuff.h
@@ -483,10 +483,6 @@ extern int skb_cow_data(struct sk
extern int skb_pad(struct sk_buff *skb, int pad);
#define dev_kfree_skb(a) consume_skb(a)
#define dev_consume_skb(a) kfree_skb_clean(a)
-extern void skb_over_panic(struct sk_buff *skb, int len,
- void *here);
-extern void skb_under_panic(struct sk_buff *skb, int len,
- void *here);
extern int skb_append_datato_frags(struct sock *sk, struct sk_buff *skb,
int getfrag(void *from, char *to, int offset,
@@ -1120,7 +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);
@@ -1130,7 +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;
@@ -1138,6 +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
@@ -103,51 +103,6 @@ static struct pipe_buf_operations sock_p
.get = sock_pipe_buf_get,
};
-/*
- * Keep out-of-line to prevent kernel bloat.
- * __builtin_return_address is not used because it is not always
- * reliable.
- */
-
-/**
- * skb_over_panic - private function
- * @skb: buffer
- * @sz: size
- * @here: address
- *
- * Out of line support code for skb_put(). Not user callable.
- */
-void skb_over_panic(struct sk_buff *skb, int sz, void *here)
-{
- printk(KERN_EMERG "skb_over_panic: text:%p len:%d put:%d head:%p "
- "data:%p tail:%#lx end:%#lx dev:%s\n",
- here, skb->len, sz, skb->head, skb->data,
- (unsigned long)skb->tail, (unsigned long)skb->end,
- skb->dev ? skb->dev->name : "<NULL>");
- BUG();
-}
-EXPORT_SYMBOL(skb_over_panic);
-
-/**
- * skb_under_panic - private function
- * @skb: buffer
- * @sz: size
- * @here: address
- *
- * Out of line support code for skb_push(). Not user callable.
- */
-
-void skb_under_panic(struct sk_buff *skb, int sz, void *here)
-{
- printk(KERN_EMERG "skb_under_panic: text:%p len:%d put:%d head:%p "
- "data:%p tail:%#lx end:%#lx dev:%s\n",
- here, skb->len, sz, skb->head, skb->data,
- (unsigned long)skb->tail, (unsigned long)skb->end,
- skb->dev ? skb->dev->name : "<NULL>");
- BUG();
-}
-EXPORT_SYMBOL(skb_under_panic);
-
/* Allocate a new skbuff. We do this ourselves so we can fill in a few
* 'private' fields and also do memory statistics to find all the
* [BEEP] leaks.
@@ -1000,46 +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;
- if (unlikely(skb->tail > skb->end))
- skb_over_panic(skb, len, __builtin_return_address(0));
- 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;
- if (unlikely(skb->data<skb->head))
- skb_under_panic(skb, len, __builtin_return_address(0));
- 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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