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[NET]: convert network timestamps to ktime_t

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We currently use a special structure (struct skb_timeval) and plain
'struct timeval' to store packet timestamps in sk_buffs and struct
sock.

This has some drawbacks :
- Fixed resolution of micro second.
- Waste of space on 64bit platforms where sizeof(struct timeval)=16

I suggest using ktime_t that is a nice abstraction of high resolution
time services, currently capable of nanosecond resolution.

As sizeof(ktime_t) is 8 bytes, using ktime_t in 'struct sock' permits
a 8 byte shrink of this structure on 64bit architectures. Some other
structures also benefit from this size reduction (struct ipq in
ipv4/ip_fragment.c, struct frag_queue in ipv6/reassembly.c, ...)

Once this ktime infrastructure adopted, we can more easily provide
nanosecond resolution on top of it. (ioctl SIOCGSTAMPNS and/or
SO_TIMESTAMPNS/SCM_TIMESTAMPNS)

Note : this patch includes a bug correction in
compat_sock_get_timestamp() where a "err = 0;" was missing (so this
syscall returned -ENOENT instead of 0)

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
CC: Stephen Hemminger <shemminger@linux-foundation.org>
CC: John find <linux.kernel@free.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet
2007-04-19 16:16:32 -07:00
committed by David S. Miller
parent 3927f2e8f9
commit b7aa0bf70c
20 changed files with 85 additions and 98 deletions
Download Patch File Download Diff File Expand all files Collapse all files

26
include/linux/skbuff.h
View File

@@ -27,6 +27,7 @@
#include <net/checksum.h>
#include <linux/rcupdate.h>
#include <linux/dmaengine.h>
#include <linux/hrtimer.h>
#define HAVE_ALLOC_SKB /* For the drivers to know */
#define HAVE_ALIGNABLE_SKB /* Ditto 8) */
@@ -156,11 +157,6 @@ struct skb_shared_info {
#define SKB_DATAREF_SHIFT 16
#define SKB_DATAREF_MASK ((1 << SKB_DATAREF_SHIFT) - 1)
struct skb_timeval {
u32 off_sec;
u32 off_usec;
};
enum {
SKB_FCLONE_UNAVAILABLE,
@@ -233,7 +229,7 @@ struct sk_buff {
struct sk_buff *prev;
struct sock *sk;
struct skb_timeval tstamp;
ktime_t tstamp;
struct net_device *dev;
int iif;
/* 4 byte hole on 64 bit*/
@@ -1365,26 +1361,14 @@ extern void skb_add_mtu(int mtu);
*/
static inline void skb_get_timestamp(const struct sk_buff *skb, struct timeval *stamp)
{
stamp->tv_sec = skb->tstamp.off_sec;
stamp->tv_usec = skb->tstamp.off_usec;
*stamp = ktime_to_timeval(skb->tstamp);
}
/**
* skb_set_timestamp - set timestamp of a skb
* @skb: skb to set stamp of
* @stamp: pointer to struct timeval to get stamp from
*
* Timestamps are stored in the skb as offsets to a base timestamp.
* This function converts a struct timeval to an offset and stores
* it in the skb.
*/
static inline void skb_set_timestamp(struct sk_buff *skb, const struct timeval *stamp)
static inline void __net_timestamp(struct sk_buff *skb)
{
skb->tstamp.off_sec = stamp->tv_sec;
skb->tstamp.off_usec = stamp->tv_usec;
skb->tstamp = ktime_get_real();
}
extern void __net_timestamp(struct sk_buff *skb);
extern __sum16 __skb_checksum_complete(struct sk_buff *skb);