From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ingo Molnar Subject: Re: [patch] voluntary-preempt-2.6.9-rc1-bk4-Q8 Date: Thu, 2 Sep 2004 09:15:25 +0200 Sender: linux-kernel-owner@vger.kernel.org Message-ID: <20040902071525.GA19925@elte.hu> References: <20040902063335.GA17657@elte.hu> <20040902065549.GA18860@elte.hu> <1094108653.11364.26.camel@krustophenia.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <1094108653.11364.26.camel@krustophenia.net> To: Lee Revell Cc: Mark_H_Johnson@raytheon.com, "K.R. Foley" , linux-kernel , Felipe Alfaro Solana , Daniel Schmitt , alsa-devel List-Id: alsa-devel@alsa-project.org * Lee Revell wrote: > Here are traces of a 145, 190, and 217 usec latencies in > netif_receive_skb: > > http://krustophenia.net/testresults.php?dataset=2.6.9-rc1-Q6#/var/www/2.6.9-rc1-Q6/trace2.txt > http://krustophenia.net/testresults.php?dataset=2.6.9-rc1-Q6#/var/www/2.6.9-rc1-Q6/trace3.txt > http://krustophenia.net/testresults.php?dataset=2.6.9-rc1-Q6#/var/www/2.6.9-rc1-Q6/trace4.txt these all seem to be single-packet processing latencies - it would be quite hard to make those codepaths preemptible. i'd suggest to turn off things like netfilter and ip_conntrack (and other optional networking features that show up in the trace), they can only increase latency: 00000001 0.016ms (+0.000ms): ip_rcv (netif_receive_skb) 00000001 0.019ms (+0.002ms): nf_hook_slow (ip_rcv) 00000002 0.019ms (+0.000ms): nf_iterate (nf_hook_slow) 00000002 0.021ms (+0.001ms): ip_conntrack_defrag (nf_iterate) 00000002 0.022ms (+0.000ms): ip_conntrack_in (nf_iterate) 00000002 0.022ms (+0.000ms): ip_ct_find_proto (ip_conntrack_in) 00000103 0.023ms (+0.000ms): __ip_ct_find_proto (ip_ct_find_proto) 00000102 0.024ms (+0.000ms): local_bh_enable (ip_ct_find_proto) 00000002 0.025ms (+0.001ms): tcp_error (ip_conntrack_in) Ingo