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- Regression - Unable to receive packets if MTU == 1500

3.5/6.x Shawn Starr 1 participant 1 message Dec 3, 2012 1 message not in the archive

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Shawn Starr

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Quoted 1 line · Shawn Starr

Hello network driver folks,

To follow up, this is fixed now in 3.6.7-5.fc18.x86_64

[38936.525226] e1000e 0000:00:19.0: eth0: changing MTU from 9000 to 1500
[38936.539510] e1000e 0000:00:19.0: Interrupt Throttle Rate turned on
[38939.352053] e1000e: eth0 NIC Link is Up 1000 Mbps Full Duplex, Flow

Control: Rx/Tx

I don't remember which 3.6 -rc fixed it but I saw some adjustments in e1000e threshold changes in Linus's usual announce -rc emails.

Thanks for fixing! Now onto Fedora 19 (3.7) kernel testing

Shawn.

Quoted 73 lines

I recently decided to reinstall my Lenovo W500 laptop and found I wasn't able to get DHCP leases, I wasn't able to install over PXE (when getting the IP a second time within the OS)

Fedora is currently using kernel-3.6.2-2.fc18.x86_64 (Pre-beta)

The only difference I noticed was in my old install of Fedora, I had added MTU=9000 to the interface config while using a 3.5 kernel, not knowing 3.6.x seems to break things.

My Cisco DPC3825 Switch/Cable modem has an MTU setting but this is from Cable provider <-> WAN interface only. I tried changing to 1500 but by default it uses this anyway.

I had noticed tx unit hang errors sometimes, but not when MTU is above 1500.

PCI info:

00:19.0 Ethernet controller: Intel Corporation 82567LM Gigabit Network Connection (rev 03)
Subsystem: Lenovo Device 20ee
Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr-
Stepping- SERR+ FastB2B- DisINTx+
Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort-
<TAbort- <MAbort- >SERR- <PERR- INTx-
Latency: 0
Interrupt: pin A routed to IRQ 46
Region 0: Memory at fc000000 (32-bit, non-prefetchable) [size=128K] Region 1: Memory at fc025000 (32-bit, non-prefetchable) [size=4K] Region 2: I/O ports at 1840 [size=32]
Capabilities: [c8] Power Management version 2
Flags: PMEClk- DSI+ D1- D2- AuxCurrent=0mA
PME(D0+,D1-,D2-,D3hot+,D3cold+)
Status: D0 NoSoftRst- PME-Enable- DSel=0 DScale=1 PME-
Capabilities: [d0] MSI: Enable+ Count=1/1 Maskable- 64bit+
Address: 00000000fee0100c Data: 41a2
Capabilities: [e0] PCI Advanced Features
AFCap: TP+ FLR+
AFCtrl: FLR-
AFStatus: TP-
Kernel driver in use: e1000e

e1000e conversation log:

[   12.653816] e1000e: Intel(R) PRO/1000 Network Driver - 2.0.0-k
[   12.653819] e1000e: Copyright(c) 1999 - 2012 Intel Corporation.
[   12.653855] e1000e 0000:00:19.0: setting latency timer to 64
[   12.653938] e1000e 0000:00:19.0: Interrupt Throttling Rate (ints/sec) set
to dynamic conservative mode
[   12.653980] e1000e 0000:00:19.0: irq 46 for MSI/MSI-X
[   12.844121] e1000e 0000:00:19.0: eth0: (PCI Express:2.5GT/s:Width x1)
00:22:68:0c:96:e3
[   12.844124] e1000e 0000:00:19.0: eth0: Intel(R) PRO/1000 Network

Connection [ 12.844150] e1000e 0000:00:19.0: eth0: MAC: 7, PHY: 8, PBA
No: 1008FF-0FF [ 17.459570] e1000e 0000:00:19.0: eth0: changing MTU from
1500 to 9000 [ 17.459577] e1000e 0000:00:19.0: Interrupt Throttle Rate
turned off [ 17.948121] e1000e 0000:00:19.0: irq 46 for MSI/MSI-X

[   18.049164] e1000e 0000:00:19.0: irq 46 for MSI/MSI-X
[   20.442936] e1000e: eth0 NIC Link is Up 1000 Mbps Full Duplex, Flow

Control: Rx/Tx

When I set MTU = 1500 (2000 works), it will stop receiving packets, it also disables Interrupt Throttling when MTU is set higher.

After testing reasons why it wasn't get a DHCP lease, I decided to bump the MTU to 9000 for Jumbo Frames and as soon as I did this, I was able to get a lease and the network functioned resumes receiving packets.

Can anyone else report regressions or might know whats going on?

Thanks,
Shawn.