Re: Network performance degradation from 2.6.11.12 to 2.6.16.20

[Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>]

Hello!

> But that never happens right? 

Right.

Well, not right. It happens. Simply because you get packet
with newer timestamp after previous handler saw this packet
and did some actions. I just do not see any bad consequences.


> And do you have some other prefered way to solve this? Even if the timer
> was fast it would be still good to avoid it in the fast path when DHCPD
> is running.

No. The way, which you suggested, seems to be the best.


1. It even does not disable possibility to record timestamp inside
   driver, which Alan was afraid of. The sequence is:

	if (!skb->tstamp.off_sec)
                net_timestamp(skb);

2. Maybe, netif_rx() should continue to get timestamp in netif_rx().

3. NAPI already introduced almost the same inaccuracy. And it is really
   silly to waste time getting timestamp in netif_receive_skb() a few
   moments before the packet is delivered to a socket.

4. ...but clock source, which takes one of top lines in profiles
   must be repaired yet. :-)

Alexey
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