On Fri, Aug 18, 2006 at 08:43:08AM +0300, John Que ([EMAIL PROTECTED]) wrote:
> Following your answer I tried adding a call to net_enable_timestamp() in
> a module I wrote which use NF_HOOKS.
> This is what is done , for example, in ipq_rcv_skb(struct sk_buff *skb)
> in linux-2.6.14 in net/ipv4/netfilter/ip_queue.c.
>
> After doing so I get timestamps which are not 0.
>
> what I wonder now is :
> 1) does this have ANY performance implication (when dealing with a
> high network load which can get to 50,000 packets per second?
Yes, it has. do_gettimeofday() is quite slow on some processors and is
not SMP-friendly.
> 2) It does work as I said, but I want to be cautios: Am I permitted to
> add this method ? are there any implications for adding this method
> which can create troubles ?
> I must say that I am NOT changing anywhere the timestamp; it's only
> for statistics.
If you add ata least on socket with SO_TIMESTAMP option, it will enable
timestamps for all skbs, so you have not created any wrong thing, except
that slowed down your network processing.
> Regards,
> John
--
Evgeniy Polyakov
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