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[Xen-users] High ping time from domU , normal time when tcpdump is running

From: Javier Barroso <javibarroso@xxxxxxxxx>

Date: Fri, 6 Nov 2009 11:12:26 +0100

Delivery-date: Fri, 06 Nov 2009 02:13:08 -0800

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HI, I'm having trouble with a debian etch HVM domU inside a dom0 domu >From domU, I try to ping gateway, but response time change if tcpdump is writing to standard output. Ping without tcpdump running has a 4 ms time. While tcpdump is writing in stdout, in another terminal: # ping -n -c20 10.12.6.1 PING 10.12.6.1 (10.12.6.1) 56(84) bytes of data. 64 bytes from 10.12.6.1: icmp_seq=1 ttl=64 time=0.448 ms 64 bytes from 10.12.6.1: icmp_seq=2 ttl=64 time=0.421 ms 64 bytes from 10.12.6.1: icmp_seq=3 ttl=64 time=0.405 ms 64 bytes from 10.12.6.1: icmp_seq=4 ttl=64 time=0.418 ms 64 bytes from 10.12.6.1: icmp_seq=5 ttl=64 time=0.423 ms 64 bytes from 10.12.6.1: icmp_seq=6 ttl=64 time=0.414 ms 64 bytes from 10.12.6.1: icmp_seq=7 ttl=64 time=0.411 ms 64 bytes from 10.12.6.1: icmp_seq=8 ttl=64 time=0.400 ms 64 bytes from 10.12.6.1: icmp_seq=9 ttl=64 time=0.427 ms 64 bytes from 10.12.6.1: icmp_seq=10 ttl=64 time=0.408 ms 64 bytes from 10.12.6.1: icmp_seq=11 ttl=64 time=0.461 ms 64 bytes from 10.12.6.1: icmp_seq=12 ttl=64 time=0.420 ms 64 bytes from 10.12.6.1: icmp_seq=13 ttl=64 time=0.389 ms 64 bytes from 10.12.6.1: icmp_seq=14 ttl=64 time=0.424 ms 64 bytes from 10.12.6.1: icmp_seq=15 ttl=64 time=0.412 ms 64 bytes from 10.12.6.1: icmp_seq=16 ttl=64 time=0.398 ms 64 bytes from 10.12.6.1: icmp_seq=17 ttl=64 time=0.388 ms 64 bytes from 10.12.6.1: icmp_seq=18 ttl=64 time=0.403 ms 64 bytes from 10.12.6.1: icmp_seq=19 ttl=64 time=0.413 ms 64 bytes from 10.12.6.1: icmp_seq=20 ttl=64 time=0.404 ms --- 10.12.6.1 ping statistics --- 20 packets transmitted, 20 received, 0% packet loss, time 19000ms rtt min/avg/max/mdev = 0.388/0.414/0.461/0.024 ms With tcpdump -wfile icmp in one terminal and ping in another: # ping -n -c20 10.12.6.1 PING 10.12.6.1 (10.12.6.1) 56(84) bytes of data. 64 bytes from 10.12.6.1: icmp_seq=1 ttl=64 time=2.35 ms 64 bytes from 10.12.6.1: icmp_seq=2 ttl=64 time=4.11 ms 64 bytes from 10.12.6.1: icmp_seq=3 ttl=64 time=4.12 ms 64 bytes from 10.12.6.1: icmp_seq=4 ttl=64 time=4.16 ms 64 bytes from 10.12.6.1: icmp_seq=5 ttl=64 time=4.16 ms 64 bytes from 10.12.6.1: icmp_seq=6 ttl=64 time=0.398 ms 64 bytes from 10.12.6.1: icmp_seq=7 ttl=64 time=4.18 ms 64 bytes from 10.12.6.1: icmp_seq=8 ttl=64 time=4.16 ms 64 bytes from 10.12.6.1: icmp_seq=9 ttl=64 time=4.16 ms 64 bytes from 10.12.6.1: icmp_seq=10 ttl=64 time=4.15 ms 64 bytes from 10.12.6.1: icmp_seq=11 ttl=64 time=4.15 ms 64 bytes from 10.12.6.1: icmp_seq=12 ttl=64 time=4.15 ms 64 bytes from 10.12.6.1: icmp_seq=13 ttl=64 time=4.19 ms 64 bytes from 10.12.6.1: icmp_seq=14 ttl=64 time=4.16 ms 64 bytes from 10.12.6.1: icmp_seq=15 ttl=64 time=4.16 ms 64 bytes from 10.12.6.1: icmp_seq=16 ttl=64 time=4.16 ms 64 bytes from 10.12.6.1: icmp_seq=17 ttl=64 time=4.15 ms 64 bytes from 10.12.6.1: icmp_seq=18 ttl=64 time=4.14 ms 64 bytes from 10.12.6.1: icmp_seq=19 ttl=64 time=4.18 ms 64 bytes from 10.12.6.1: icmp_seq=20 ttl=64 time=4.15 ms --- 10.12.6.1 ping statistics --- 20 packets transmitted, 20 received, 0% packet loss, time 19003ms rtt min/avg/max/mdev = 0.398/3.881/4.197/0.893 ms Without any tcpdump running: # ping -n -c20 10.12.6.1 PING 10.12.6.1 (10.12.6.1) 56(84) bytes of data. 64 bytes from 10.12.6.1: icmp_seq=1 ttl=64 time=1.26 ms 64 bytes from 10.12.6.1: icmp_seq=2 ttl=64 time=4.13 ms 64 bytes from 10.12.6.1: icmp_seq=3 ttl=64 time=4.16 ms 64 bytes from 10.12.6.1: icmp_seq=4 ttl=64 time=4.16 ms 64 bytes from 10.12.6.1: icmp_seq=5 ttl=64 time=4.16 ms 64 bytes from 10.12.6.1: icmp_seq=6 ttl=64 time=4.00 ms 64 bytes from 10.12.6.1: icmp_seq=7 ttl=64 time=4.16 ms 64 bytes from 10.12.6.1: icmp_seq=8 ttl=64 time=4.13 ms 64 bytes from 10.12.6.1: icmp_seq=9 ttl=64 time=4.16 ms 64 bytes from 10.12.6.1: icmp_seq=10 ttl=64 time=4.15 ms 64 bytes from 10.12.6.1: icmp_seq=11 ttl=64 time=4.16 ms 64 bytes from 10.12.6.1: icmp_seq=12 ttl=64 time=4.16 ms 64 bytes from 10.12.6.1: icmp_seq=13 ttl=64 time=4.16 ms 64 bytes from 10.12.6.1: icmp_seq=14 ttl=64 time=4.13 ms 64 bytes from 10.12.6.1: icmp_seq=15 ttl=64 time=4.15 ms 64 bytes from 10.12.6.1: icmp_seq=16 ttl=64 time=4.16 ms 64 bytes from 10.12.6.1: icmp_seq=17 ttl=64 time=4.16 ms 64 bytes from 10.12.6.1: icmp_seq=18 ttl=64 time=4.16 ms 64 bytes from 10.12.6.1: icmp_seq=19 ttl=64 time=4.16 ms 64 bytes from 10.12.6.1: icmp_seq=20 ttl=64 time=4.12 ms --- 10.12.6.1 ping statistics --- 20 packets transmitted, 20 received, 0% packet loss, time 19002ms rtt min/avg/max/mdev = 1.260/4.003/4.164/0.630 ms Could be a cpu issue ? I think no because uptime tells: load average: 0.24, 0.16, 0.18 and nice -n20 doesn't help here. But I read about cpu won't dedicate enought time to network card .. I can't get my domU with two cpus, does it should works ? dom0 # grep cpu|net /etc/xen/domU vcpus=2 cpus = "1,2" dom0# xm vcpu-list domU Name ID VCPUs CPU State Time(s) CPU Affinity domU 4 0 3 -b- 23103.3 1-4 domU 4 1 - --p 0.0 1-4 dom0 # dpkg -l | grep xen ... ii xen-linux-system-2.6.18-6-xen-amd64 2.6.18.dfsg.1-24etch4 XEN system with Linux 2.6.18 image on AMD64 ii xen-ioemu-3.0.3-1 3.0.3-0-4 XEN administrative tools ii xen-hypervisor-3.0.3-1-amd64 3.0.3-0-4 The Xen Hypervisor on AMD64 domU# # ethtool -i eth0 driver: 8139cp version: 1.2 firmware-version: bus-info: 0000:00:04.0 domU# uname -a Linux domU 2.6.18-6-686 #1 SMP Sat Dec 27 09:31:05 UTC 2008 i686 GNU/Linux # cat /proc/cpuinfo processor : 0 vendor_id : GenuineIntel cpu family : 6 model : 15 model name : Intel(R) Xeon(R) CPU L5310 @ 1.60GHz stepping : 7 cpu MHz : 1596.067 cache size : 4096 KB fdiv_bug : no hlt_bug : no f00f_bug : no coma_bug : no fpu : yes fpu_exception : yes cpuid level : 10 wp : yes flags : fpu vme de pse tsc msr mce cx8 sep mtrr pge mca cmov pat clflush dts mmx fxsr sse sse2 ss pbe syscall nx lm constant_tsc up pni ds_cpl cx16 xtpr lahf_lm bogomips : 3198.72 Could be a interrupts? I don't known how study that :( I post cat /proc/interrupts (maybe it can help ?) # cat /proc/interrupts CPU0 0: 37770417 XT-PIC timer 1: 9 XT-PIC i8042 2: 0 XT-PIC cascade 11: 2847259 XT-PIC eth0 12: 110 XT-PIC i8042 14: 521293 XT-PIC ide0 Note that I'm having trouble too with other hvm machine which too go to the pass in the time and keep hangs with black screen when I try to connect to vnc and I have to turn off and turn on it. I'm thinking in go to paravirtualization both machines. I tried playing with acpi=off and noapic as kernel parameters but nothing happens Any pointer ? Thanks ! _______________________________________________ Xen-users mailing list Xen-users@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-users

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