Gregory Wright wrote: > (Note: long message) > > Hi, > > The tcp duplicate ACK attack is back. > > Last March, there was a thread on duplicate TCP acks in -CURRENT. > I have been able to reproduce the problem on 7.0-BETA2 (amd64) > and have some new information that might help locate the bug. > > Background: I first noticed problems with tcp connections dropping > when Bacula was running on our backup server. The hardware was > a dual Opteron 244, 2 GB RAM, running FreeBSD 6.2-RELEASE-p2. > The ethernet NIC was a bge. > > We went through an extensive process to rule out hardware and cabling > problems: the server hardware was replaced with a single Opteron 270 > (dual core) on a Tyan S2882-D motherboard. The memory was replaced > as well. The NICs are still bge. This machine is "hardtack". This may be a TSO bug in the bge hardware. Please repeat your tests in the original setup with TSO disabled on the bge interfaces ("ifconfig bgeX -tso"). Second if you've got another network card with something else than bge please put it into the same box and run the tests as well. -- Andre > We have another server in the same rack, a dual Opteron 2214, 4 GB RAM, > running FreeBSD 6.2-RELEASE-p1. It has never shown the "dropped > connection" problem. This machine is "greenhouse-george" > > All of the machines are on a single LAN, with a Nortel BayStack 450-24T > ethernet switch. > > Experiments: > > The first experiment was to use netperf to send a tcp stream from either > a PowerBook G4 (OS X 10.4.10) or a dual Intel Clovertown box running > FreeBSD 6.2-RELEASE-p8. This is from the PowerBook: > > crossroads-able> netperf -H greenhouse-george > TCP STREAM TEST from localhost (0.0.0.0) port 0 AF_INET to greenhouse- > george.18clay.com (192.168.2.63) port 0 AF_INET > Recv Send Send > Socket Socket Message Elapsed > Size Size Size Time Throughput > bytes bytes bytes secs. 10^6bits/sec > > 65536 262144 262144 10.02 93.77 > crossroads-able> netperf -H hardtack > TCP STREAM TEST from localhost (0.0.0.0) port 0 AF_INET to hardtack. > 18clay.com (192.168.2.61) port 0 AF_INET > Recv Send Send > Socket Socket Message Elapsed > Size Size Size Time Throughput > bytes bytes bytes secs. 10^6bits/sec > > 65536 262144 262144 10.10 29.24 > crossroads-able> > > (That there is a problem in the second case is easy to see just > from the ethernet switch: the activity lights blink on and off. A > wireshark > trace shows a duplicate ACK storm and gaps in the transmitted > packet stream.) > > Just to be certain that this isn't a weird cabling problem, I swapped the > cables to the two machines: > > crossroads-able> netperf -H greenhouse-george > TCP STREAM TEST from localhost (0.0.0.0) port 0 AF_INET to greenhouse- > george.18clay.com (192.168.2.63) port 0 AF_INET > Recv Send Send > Socket Socket Message Elapsed > Size Size Size Time Throughput > bytes bytes bytes secs. 10^6bits/sec > > 65536 262144 262144 10.02 92.68 > crossroads-able> netperf -H hardtack > TCP STREAM TEST from localhost (0.0.0.0) port 0 AF_INET to hardtack. > 18clay.com (192.168.2.61) port 0 AF_INET > Recv Send Send > Socket Socket Message Elapsed > Size Size Size Time Throughput > bytes bytes bytes secs. 10^6bits/sec > > 65536 262144 262144 10.02 30.86 > crossroads-able> > > The low throughput (and gaps in the tcp stream) stay with the > machine rather than moving with the cable. > > When I use my dual Clovertown box (FreeBSD 6.2-RELEASE-p8, > em NIC), as a source, I get > > ivy-mike# netperf -H greenhouse-george > TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to greenhouse- > george.18clay.com (192.168.2.63) port 0 AF_INET > Recv Send Send > Socket Socket Message Elapsed > Size Size Size Time Throughput > bytes bytes bytes secs. 10^6bits/sec > > 65536 32768 32768 10.58 94.14 > ivy-mike# netperf -H hardtack > TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to hardtack. > 18clay.com (192.168.2.61) port 0 AF_INET > Recv Send Send > Socket Socket Message Elapsed > Size Size Size Time Throughput > bytes bytes bytes secs. 10^6bits/sec > > 65536 32768 32768 10.57 89.15 > ivy-mike# > > > FreeBSD seems not as disturbed by the extra ACKs as OS X, > but I still see the activity lights on the switch blinking, indicating > dropouts in the tcp stream. Also, longer tests using either > source machine almost always result in failure ("Broken Pipe") > after a few minutes. > > Now is where things get interesting. If I connect the PowerBook > to hardtack (the machine showing the bug) with just a cable, > bypassing the switch, I get > > crossroads-able> netperf -H 192.168.2.2 -l 300 > TCP STREAM TEST from (null) (0.0.0.0) port 0 AF_INET to (null) > (192.168.2.2) port 0 AF_INET > Recv Send Send > Socket Socket Message Elapsed > Size Size Size Time Throughput > bytes bytes bytes secs. 10^6bits/sec > > 65536 262144 262144 300.54 330.45 > crossroads-able> > > The higher throughput is because I have two GbE interfaces > directly connected, instead of going through the 10/100 Mb > switch. The key thing is that I can run this test for hours without > the connection dropping. (I have run it for as long as 10000 seconds.) > And the wireshark log shows no duplicate ACK storm. > > Is there perhaps something wrong with the switch? I swapped > out our BayStack 450-24T for an identical unit with the same > results. I also have an unmanaged SMC EZ Switch 10/100, so > I tried a minimal setup: > > PowerBook <----> SMC switch <----> FreeBSD 7.0-BETA2 server (hardtack) > > Only the PowerBook and FreeBSD server are connected > to the switch. A netperf tcp streaming test gives: > > crossroads-able> netperf -H 192.168.2.2 > TCP STREAM TEST from (null) (0.0.0.0) port 0 AF_INET to (null) > (192.168.2.2) port 0 AF_INET > Recv Send Send > Socket Socket Message Elapsed > Size Size Size Time Throughput > bytes bytes bytes secs. 10^6bits/sec > > 65536 262144 262144 10.02 24.25 > crossroads-able> > > The throughput is low, but most importantly, the wireshark > log shows that the duplicate ACK storm is back. > > So is there something coming _out_ of the switch that FreeBSD's network > stack doesn't like? No, this doesn't seem to be the case. The old > SMC switch doesn't even send out spanning tree packets. > > Next experiment: netperf tcp stream from the PowerBook, but > with the interface forced into 100TX full duplex. Result: > crossroads-able> netperf -H 192.168.2.2 > > TCP STREAM TEST from (null) (0.0.0.0) port 0 AF_INET to (null) > (192.168.2.2) port 0 AF_INET > Recv Send Send > Socket Socket Message Elapsed > Size Size Size Time Throughput > bytes bytes bytes secs. 10^6bits/sec > > 65536 262144 262144 10.02 33.81 > crossroads-able> > > So the throughput has dropped and the wireshark log shows > duplicate ACK storms again. > > If I force the PowerBook to 100TX half duplex the wireshark log > still shows duplicate ACK storms. And at 10 Mb/s, full or half duplex, > I see still bursts of duplicate ACKs. > > One last thing to note is that I can run netperf tests _from_ the > buggy machine to the laptop with no trouble. Again forcing the > PowerBook interface to 100TX full duplex, > > TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 192.168.2.1 > (192.168.2.1) port 0 AF_INET > Recv Send Send > Socket Socket Message Elapsed > Size Size Size Time Throughput > bytes bytes bytes secs. 10^6bits/sec > > 262144 32768 32768 10.02 93.03 > hardtack# > > The wireshark logs show no duplicate ACKs. > > One interesting thing is that the packet logs for the reverse > (properly working) case show a more regular structure of > data and ACK packets. In the forward (buggy) direction, > the data packets are burstier, and to my eye more irregular. > This was mentioned in passing in the original thread, in which > someone speculated that there might be a window problem. > > So, in sum: > > The duplicate ack problem happens on my FreeBSD 7.0-BETA2 > machine (single Opteron 270, Tyan S2882-D, 2 GB RAM) when the > bge interface in operating in 10 or 100 Mb/s mode, but not in > Gb mode. > > It does not happen on my FreeBSD 6.2-RELEASE-p1 box > (dual Opteron 2214, Tyan 3992G3NR, 4 GB RAM) which > has a bge NIC as well. Nor does it happen on my dual > Clovertown box (dual E5345, Tyan S2696A2NRF, 4 GB) > with em NIC. > > The buggy machine is not much use to me until this problem can be > fixed, so I can dedicate it to debugging for a while. Any hints > about where code might be instrumented to track the bug down or > new experiments to perform are welcome. > > I can provide wireshark logs; compressed they are not too > large (a few MB). > > Here is the dmesg of the buggy machine: > > hardtack# dmesg > Copyright (c) 1992-2007 The FreeBSD Project. > Copyright (c) 1979, 1980, 1983, 1986, 1988, 1989, 1991, 1992, 1993, 1994 > The Regents of the University of California. All rights reserved. > FreeBSD is a registered trademark of The FreeBSD Foundation. > FreeBSD 7.0-BETA2 #0: Fri Nov 2 14:54:38 UTC 2007 > root_at_myers.cse.buffalo.edu:/usr/obj/usr/src/sys/GENERIC > Timecounter "i8254" frequency 1193182 Hz quality 0 > CPU: Dual Core AMD Opteron(tm) Processor 270 HE (1993.41-MHz K8-class CPU) > Origin = "AuthenticAMD" Id = 0x20f12 Stepping = 2 > > Features=0x178bfbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE > ,MCA,CMOV,PAT,PSE36,CLFLUSH,MMX,FXSR,SSE,SSE2,HTT> > Features2=0x1<SSE3> > AMD Features=0xe2500800<SYSCALL,NX,MMX+,FFXSR,LM,3DNow!+,3DNow!> > AMD Features2=0x3<LAHF,CMP> > Cores per package: 2 > usable memory = 2134962176 (2036 MB) > avail memory = 2060251136 (1964 MB) > ACPI APIC Table: <A M I OEMAPIC > > FreeBSD/SMP: Multiprocessor System Detected: 2 CPUs > cpu0 (BSP): APIC ID: 0 > cpu1 (AP): APIC ID: 1 > MADT: Forcing active-low polarity and level trigger for SCI > ioapic0 <Version 1.1> irqs 0-23 on motherboard > ioapic1 <Version 1.1> irqs 24-27 on motherboard > ioapic2 <Version 1.1> irqs 28-31 on motherboard > kbd1 at kbdmux0 > ath_hal: 0.9.20.3 (AR5210, AR5211, AR5212, RF5111, RF5112, RF2413, RF5413) > acpi0: <A M I OEMXSDT> on motherboard > acpi0: [ITHREAD] > acpi0: Power Button (fixed) > acpi0: reservation of 0, a0000 (3) failed > acpi0: reservation of 100000, 7ff00000 (3) failed > Timecounter "ACPI-fast" frequency 3579545 Hz quality 1000 > acpi_timer0: <24-bit timer at 3.579545MHz> port 0x1008-0x100b on acpi0 > acpi_hpet0: <High Precision Event Timer> iomem 0xfec01000-0xfec013ff on > acpi0 > Timecounter "HPET" frequency 14318180 Hz quality 900 > cpu0: <ACPI CPU> on acpi0 > acpi_throttle0: <ACPI CPU Throttling> on cpu0 > powernow0: <Cool`n'Quiet K8> on cpu0 > cpu1: <ACPI CPU> on acpi0 > powernow1: <Cool`n'Quiet K8> on cpu1 > pcib0: <ACPI Host-PCI bridge> port 0xcf8-0xcff on acpi0 > pci0: <ACPI PCI bus> on pcib0 > pcib1: <ACPI PCI-PCI bridge> at device 6.0 on pci0 > pci3: <ACPI PCI bus> on pcib1 > ohci0: <OHCI (generic) USB controller> mem 0xfeafb000-0xfeafbfff irq 19 > at device 0.0 on pci3 > ohci0: [GIANT-LOCKED] > ohci0: [ITHREAD] > usb0: OHCI version 1.0, legacy support > usb0: <OHCI (generic) USB controller> on ohci0 > usb0: USB revision 1.0 > uhub0: <AMD OHCI root hub, class 9/0, rev 1.00/1.00, addr 1> on usb0 > uhub0: 3 ports with 3 removable, self powered > ohci1: <OHCI (generic) USB controller> mem 0xfeafc000-0xfeafcfff irq 19 > at device 0.1 on pci3 > ohci1: [GIANT-LOCKED] > ohci1: [ITHREAD] > usb1: OHCI version 1.0, legacy support > usb1: <OHCI (generic) USB controller> on ohci1 > usb1: USB revision 1.0 > uhub1: <AMD OHCI root hub, class 9/0, rev 1.00/1.00, addr 1> on usb1 > uhub1: 3 ports with 3 removable, self powered > atapci0: <SiI 3114 SATA150 controller> port > 0xbc00-0xbc07,0xb880-0xb883,0xb800-0xb807,0xac00-0xac03,0xa880-0xa88f > mem 0xfeafec00-0xfeafefff irq 19 at device 5.0 on pci3 > atapci0: [ITHREAD] > ata2: <ATA channel 0> on atapci0 > ata2: [ITHREAD] > ata3: <ATA channel 1> on atapci0 > ata3: [ITHREAD] > ata4: <ATA channel 2> on atapci0 > ata4: [ITHREAD] > ata5: <ATA channel 3> on atapci0 > ata5: [ITHREAD] > vgapci0: <VGA-compatible display> port 0xb000-0xb0ff mem > 0xfd000000-0xfdffffff,0xfeaff000-0xfeafffff irq 18 at device 6.0 on pci3 > fxp0: <Intel 82551 Pro/100 Ethernet> port 0xa800-0xa83f mem > 0xfeafa000-0xfeafafff,0xfeaa0000-0xfeabffff irq 18 at device 8.0 on pci3 > miibus0: <MII bus> on fxp0 > inphy0: <i82555 10/100 media interface> PHY 1 on miibus0 > inphy0: 10baseT, 10baseT-FDX, 100baseTX, 100baseTX-FDX, auto > fxp0: Ethernet address: 00:e0:81:4b:3e:39 > fxp0: [ITHREAD] > isab0: <PCI-ISA bridge> at device 7.0 on pci0 > isa0: <ISA bus> on isab0 > atapci1: <AMD 8111 UDMA133 controller> port > 0x1f0-0x1f7,0x3f6,0x170-0x177,0x376,0xffa0-0xffaf at device 7.1 on pci0 > ata0: <ATA channel 0> on atapci1 > ata0: [ITHREAD] > ata1: <ATA channel 1> on atapci1 > ata1: [ITHREAD] > pci0: <serial bus, SMBus> at device 7.2 (no driver attached) > pci0: <bridge> at device 7.3 (no driver attached) > pcib2: <ACPI PCI-PCI bridge> at device 10.0 on pci0 > pci2: <ACPI PCI bus> on pcib2 > ahc0: <Adaptec 3960D Ultra160 SCSI adapter> port 0x8400-0x84ff mem > 0xfc8fd000-0xfc8fdfff irq 27 at device 3.0 on pci2 > ahc0: [ITHREAD] > aic7899: Ultra160 Wide Channel A, SCSI Id=7, 32/253 SCBs > ahc1: <Adaptec 3960D Ultra160 SCSI adapter> port 0x8800-0x88ff mem > 0xfc8fe000-0xfc8fefff irq 24 at device 3.1 on pci2 > ahc1: [ITHREAD] > aic7899: Ultra160 Wide Channel B, SCSI Id=7, 32/253 SCBs > pci0:2:9:0: bad VPD cksum, remain 72 > bge0: <Broadcom Gigabit Ethernet Controller, ASIC rev. 0x2100> mem > 0xfc870000-0xfc87ffff irq 24 at device 9.0 on pci2 > miibus1: <MII bus> on bge0 > brgphy0: <BCM5704 10/100/1000baseTX PHY> PHY 1 on miibus1 > brgphy0: 10baseT, 10baseT-FDX, 100baseTX, 100baseTX-FDX, 1000baseT, > 1000baseT-FDX, auto > bge0: Ethernet address: 00:e0:81:4b:3e:ae > bge0: [ITHREAD] > pci0:2:9:1: bad VPD cksum, remain 72 > bge1: <Broadcom Gigabit Ethernet Controller, ASIC rev. 0x2100> mem > 0xfc890000-0xfc89ffff irq 25 at device 9.1 on pci2 > miibus2: <MII bus> on bge1 > brgphy1: <BCM5704 10/100/1000baseTX PHY> PHY 1 on miibus2 > brgphy1: 10baseT, 10baseT-FDX, 100baseTX, 100baseTX-FDX, 1000baseT, > 1000baseT-FDX, auto > bge1: Ethernet address: 00:e0:81:4b:3e:af > bge1: [ITHREAD] > pcib3: <ACPI PCI-PCI bridge> at device 11.0 on pci0 > pci1: <ACPI PCI bus> on pcib3 > acpi_button0: <Power Button> on acpi0 > atkbdc0: <Keyboard controller (i8042)> port 0x60,0x64 irq 1 on acpi0 > atkbd0: <AT Keyboard> irq 1 on atkbdc0 > kbd0 at atkbd0 > atkbd0: [GIANT-LOCKED] > atkbd0: [ITHREAD] > psm0: <PS/2 Mouse> irq 12 on atkbdc0 > psm0: [GIANT-LOCKED] > psm0: [ITHREAD] > psm0: model IntelliMouse, device ID 3 > sio0: configured irq 4 not in bitmap of probed irqs 0 > sio0: port may not be enabled > sio0: configured irq 4 not in bitmap of probed irqs 0 > sio0: port may not be enabled > sio0: <16550A-compatible COM port> port 0x3f8-0x3ff irq 4 flags 0x10 on > acpi0 > sio0: type 16550A > sio0: [FILTER] > sio1: configured irq 3 not in bitmap of probed irqs 0 > sio1: port may not be enabled > sio1: configured irq 3 not in bitmap of probed irqs 0 > sio1: port may not be enabled > sio1: <16550A-compatible COM port> port 0x2f8-0x2ff irq 3 on acpi0 > sio1: type 16550A > sio1: [FILTER] > fdc0: <floppy drive controller (FDE)> port 0x3f0-0x3f5,0x3f7 irq 6 drq > 2 on acpi0 > fdc0: [FILTER] > fd0: <1440-KB 3.5" drive> on fdc0 drive 0 > orm0: <ISA Option ROMs> at iomem 0xc0000-0xc7fff,0xc8000-0xcc7ff on isa0 > ppc0: cannot reserve I/O port range > sc0: <System console> at flags 0x100 on isa0 > sc0: VGA <16 virtual consoles, flags=0x300> > vga0: <Generic ISA VGA> at port 0x3c0-0x3df iomem 0xa0000-0xbffff on isa0 > Timecounters tick every 1.000 msec > acd0: DVDROM <ATAPI DVD D DH16D2P/HP56> at ata1-master UDMA33 > ad4: 305245MB <Seagate ST3320620AS 3.AAE> at ata2-master SATA150 > Waiting 5 seconds for SCSI devices to settle > sa0 at ahc1 bus 0 target 6 lun 0 > sa0: <IBM ULTRIUM-TD2 3AYD> Removable Sequential Access SCSI-3 device > sa0: 160.000MB/s transfers (80.000MHz DT, offset 31, 16bit) > SMP: AP CPU #1 Launched! > Trying to mount root from ufs:/dev/ad4s1a > WARNING: / was not properly dismounted > ch0 at ahc1 bus 0 target 5 lun 0 > ch0: <DELL PV-122T K17r> Removable Changer SCSI-2 device > ch0: 3.300MB/s transfers > ch0: 8 slots, 1 drive, 1 picker, 0 portals > bge1: link state changed to DOWN > bge1: link state changed to UP > bge1: promiscuous mode enabled > bge1: promiscuous mode disabled > bge1: link state changed to DOWN > bge1: link state changed to UP > bge1: link state changed to DOWN > bge1: link state changed to UP > bge1: link state changed to DOWN > bge1: link state changed to UP > bge1: link state changed to DOWN > bge1: link state changed to UP > bge1: link state changed to DOWN > bge1: link state changed to UP > bge1: link state changed to DOWN > bge1: link state changed to UP > hardtack# > > > Please let me know what I can do to track this down. > > Best Wishes, > Greg > > Gregory Wright > Antiope Associates LLC > 18 Clay Street > Fair Haven, New Jersey 07704 > USA > > 1 (732) 924-4549 > 1 (732) 345-8378 [fax] > > > _______________________________________________ > freebsd-current_at_freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-current > To unsubscribe, send any mail to "freebsd-current-unsubscribe_at_freebsd.org" > >Received on Sat Nov 10 2007 - 14:55:54 UTC
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