From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alexey Kuznetsov Subject: Re: Network performance degradation from 2.6.11.12 to 2.6.16.20 Date: Tue, 19 Sep 2006 01:03:21 +0400 Message-ID: <20060918210321.GA4780@ms2.inr.ac.ru> References: <4492D5D3.4000303@atmos.washington.edu> <200609181754.37623.ak@suse.de> <20060918162847.GA4863@ms2.inr.ac.ru> <200609181850.22851.ak@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: "Vladimir B. Savkin" , Jesper Dangaard Brouer , Harry Edmon , linux-kernel@vger.kernel.org, netdev@vger.kernel.org Return-path: To: Andi Kleen Content-Disposition: inline In-Reply-To: <200609181850.22851.ak@suse.de> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org 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