From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Fri, 1 Nov 2002 21:25:49 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Fri, 1 Nov 2002 21:25:49 -0500 Received: from dyn-212-232-60-250.ppp.tiscali.fr ([212.232.60.250]:7442 "EHLO LAP") by vger.kernel.org with ESMTP id ; Fri, 1 Nov 2002 21:25:47 -0500 Message-ID: <02d101c28217$df39a1b0$0200000a@LAP> From: "Vadim Lebedev" To: Subject: Network layer mysteries Date: Sat, 2 Nov 2002 03:30:55 +0100 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2600.0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2600.0000 X-OriginalArrivalTime: 02 Nov 2002 02:30:56.0075 (UTC) FILETIME=[DF39A1B0:01C28217] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hello, I need an advize of network subsytem gourus.... I'm running uClinux 2.4.19 on 24Mhz on ATMEL AT75C310 (ARM7TDMI) processor (without cashes) with 16Bit DRAM attached The BogoMIPS is 4.59. HZ = 100 I have very strange phenomenons 1. The ping over "lo" driver is slower then ping over 8390.c based ethernet interface. 2. The RTTs reported by ping are extremely high : PING 127.0.0.1 (127.0.0.1): 56 data bytes 64 bytes from 127.0.0.1: icmp_seq=0 ttl=64 time=53.4(11.8) ms 64 bytes from 127.0.0.1: icmp_seq=1 ttl=64 time=50.4(6.1) ms 64 bytes from 127.0.0.1: icmp_seq=2 ttl=64 time=50.3(6.1) ms 64 bytes from 127.0.0.1: icmp_seq=3 ttl=64 time=50.4(6.2) ms 64 bytes from 127.0.0.1: icmp_seq=4 ttl=64 time=50.4(6.2) ms 64 bytes from 127.0.0.1: icmp_seq=5 ttl=64 time=50.3(6.1) ms 64 bytes from 127.0.0.1: icmp_seq=6 ttl=64 time=50.2(6.1) ms 64 bytes from 127.0.0.1: icmp_seq=7 ttl=64 time=50.2(6.1) ms --- 127.0.0.1 ping statistics --- 8 packets transmitted, 8 packets received, 0% packet loss round-trip min/avg/max = 50.2/50.7/53.4 ms kround-trip min/avg/max = 6.1/6.8/11.8 ms /> ping 192.168.0.10 PING 192.168.0.10 (192.168.0.10): 56 data bytes 64 bytes from 192.168.0.10: icmp_seq=0 ttl=255 time=30.5(13.4) ms 64 bytes from 192.168.0.10: icmp_seq=1 ttl=255 time=34.5(6.5) ms 64 bytes from 192.168.0.10: icmp_seq=2 ttl=255 time=34.4(6.5) ms 64 bytes from 192.168.0.10: icmp_seq=3 ttl=255 time=34.4(6.4) ms 64 bytes from 192.168.0.10: icmp_seq=4 ttl=255 time=34.3(6.5) ms 64 bytes from 192.168.0.10: icmp_seq=5 ttl=255 time=34.4(6.5) ms 64 bytes from 192.168.0.10: icmp_seq=6 ttl=255 time=34.3(6.5) ms 64 bytes from 192.168.0.10: icmp_seq=7 ttl=255 time=34.2(6.4) ms 64 bytes from 192.168.0.10: icmp_seq=8 ttl=255 time=34.3(6.5) ms --- 192.168.0.10 ping statistics --- 9 packets transmitted, 9 packets received, 0% packet loss round-trip min/avg/max = 30.5/33.9/34.5 ms kround-trip min/avg/max = 6.4/7.2/13.4 ms I've hacked ping utility to show between parenthesis the RTT calculated when using the result if SIOCGSTAMP ioctl after reading the incoming packet in addition to normal behaviour when it uses gettimeofday syscall. As you can see there is big delay between the times when packet arrives into kernel input queue and the time it is read by application. What is strange that other uClinux users running on CPUs with similar processing power does not report such kind of delays. Any idea about what happens here and what can be done about it? Please CC me the responces Thanks Vadim PS. here are results of ifconfig and route -n /> route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 192.168.0.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0 0.0.0.0 192.168.0.15 0.0.0.0 UG 0 0 0 eth0 /> ifconfig eth0 Link encap:Ethernet HWaddr 00:50:56:C3:DB:9F inet addr:192.168.0.191 Bcast:192.168.0.255 Mask:255.255.255.0 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:13 errors:0 dropped:0 overruns:0 frame:0 TX packets:13 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:100 RX bytes:1686 (1.6 kb) TX bytes:2182 (2.1 kb) Interrupt:10 Base address:0x200 lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:16 errors:0 dropped:0 overruns:0 frame:0 TX packets:16 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:1344 (1.3 kb) TX bytes:1344 (1.3 kb)