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Message-id: <4B456CC0.1000506@majjas.com>
Date: Thu, 07 Jan 2010 00:10:24 -0500
From: Michael Breuer <mbreuer@...jas.com>
To: Stephen Hemminger <shemminger@...ux-foundation.org>
Cc: Jarek Poplawski <jarkao2@...il.com>,
David Miller <davem@...emloft.net>, akpm@...ux-foundation.org,
flyboy@...il.com, linux-kernel@...r.kernel.org,
netdev@...r.kernel.org
Subject: Re: [PATCH] af_packet: Don't use skb after dev_queue_xmit()
On 1/6/2010 11:53 PM, Stephen Hemminger wrote:
> On Wed, 06 Jan 2010 23:00:34 -0500
> Michael Breuer<mbreuer@...jas.com> wrote:
>
>
>> Changing MTU to 9000, everything basically breaks - Can't use X11 (local
>> or remote - get X11 screen after gdm login locally, but then goes back
>> to greeter; remote gets no greeter); ssh sessions hang; etc. This time I
>> was able to reset the MTU back to 1500 without a reboot - but I did have
>> to ifconfig eth0 down and then up. Looking at the sk98lin code, it looks
>> to me like they do a bit more work with existing buffers before
>> completing the MTU switch. Note that even doing this, X11 did not work
>> (it did with the old mtu change code). Tried changing to mtu 4500 - same
>> effect as 9000... but when I switched back to 1500, ksoftirqd started
>> spinning using 100% of one core.
>>
> The problem is that patch was enabling scatter-gather and checksum offload
> that won't work on EC_U hardware with 9K MTU. At least, it never worked
> for me when I tested it. So because of that it really doesn't change anything
> for the better on that chip version.
>
> What version chip is on that motherboard? Mine is:
> Yukon-2 EC Ultra chip revision 3
> which corresponds to B0 step.
>
> Another possibility is the PHY register which controls number of ticks
> of buffering. The default is zero, which gives the most buffering (good),
> but the firmware could be reprogramming it (bad). In general, the driver
> doesn't fiddle with bits that are already set correctly, because sometimes
> vendors need to tweak PCI timing in firmware/BIOS. It seems the firmware on this
> chip is just a bunch of register setups done on power on.
>
So at this point, things are working as mentioned - but really slow...
at least an order of magnitude slower than with the other set of
patches. The other set also generated errors and was not stable :( But,
that set worked with mtu=9000, this set doesn't seem to work with
anything over 1500. The slowdown may also be (based on earlier testing)
attributable to Jarek's alternative #2 patch. As to the chip, I *think*
we have the same chip - I'm including lspci -vv - perhaps there is
something different.
06:00.0 Ethernet controller: Marvell Technology Group Ltd. 88E8056 PCI-E
Gigabit Ethernet Controller (rev 14)
Subsystem: Giga-byte Technology Device e000
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, Cache Line Size: 256 bytes
Interrupt: pin A routed to IRQ 58
Region 0: Memory at fbdfc000 (64-bit, non-prefetchable) [size=16K]
Region 2: I/O ports at d800 [size=256]
Expansion ROM at fbdc0000 [disabled] [size=128K]
Capabilities: [48] Power Management version 3
Flags: PMEClk- DSI- D1+ D2+ AuxCurrent=0mA
PME(D0+,D1+,D2+,D3hot+,D3cold+)
Status: D0 NoSoftRst- PME-Enable- DSel=0 DScale=1 PME-
Capabilities: [50] Vital Product Data
Product Name: Marvell Yukon 88E8056 Gigabit Ethernet
Controller
Read-only fields:
[PN] Part number: Yukon 88E8056
[EC] Engineering changes: Rev. 1.4
[MN] Manufacture ID: 4d 61 72 76 65 6c 6c
[SN] Serial number: AbCdEfG001C3B
[CP] Extended capability: 01 10 cc 03
[RV] Reserved: checksum good, 9 byte(s) reserved
Read/write fields:
[RW] Read-write area: 121 byte(s) free
End
Capabilities: [5c] MSI: Enable+ Count=1/1 Maskable- 64bit+
Address: 00000000fee00458 Data: 0000
Capabilities: [e0] Express (v1) Legacy Endpoint, MSI 00
DevCap: MaxPayload 128 bytes, PhantFunc 0, Latency L0s
unlimited, L1 unlimited
ExtTag- AttnBtn- AttnInd- PwrInd- RBE+ FLReset-
DevCtl: Report errors: Correctable- Non-Fatal- Fatal-
Unsupported-
RlxdOrd- ExtTag- PhantFunc- AuxPwr- NoSnoop-
MaxPayload 128 bytes, MaxReadReq 512 bytes
DevSta: CorrErr+ UncorrErr- FatalErr- UnsuppReq+
AuxPwr+ TransPend-
LnkCap: Port #0, Speed 2.5GT/s, Width x1, ASPM L0s L1,
Latency L0 <256ns, L1 unlimited
ClockPM+ Surprise- LLActRep- BwNot-
LnkCtl: ASPM Disabled; RCB 128 bytes Disabled- Retrain-
CommClk+
ExtSynch- ClockPM- AutWidDis- BWInt- AutBWInt-
LnkSta: Speed 2.5GT/s, Width x1, TrErr- Train- SlotClk+
DLActive- BWMgmt- ABWMgmt-
Capabilities: [100] Advanced Error Reporting
UESta: DLP- SDES- TLP- FCP- CmpltTO- CmpltAbrt-
UnxCmplt- RxOF- MalfTLP- ECRC- UnsupReq- ACSViol-
UEMsk: DLP- SDES- TLP- FCP- CmpltTO- CmpltAbrt-
UnxCmplt- RxOF- MalfTLP- ECRC- UnsupReq- ACSViol-
UESvrt: DLP+ SDES- TLP- FCP+ CmpltTO- CmpltAbrt-
UnxCmplt- RxOF+ MalfTLP+ ECRC- UnsupReq- ACSViol-
CESta: RxErr- BadTLP- BadDLLP- Rollover- Timeout-
NonFatalErr+
CEMsk: RxErr- BadTLP- BadDLLP- Rollover- Timeout-
NonFatalErr+
AERCap: First Error Pointer: 1f, GenCap- CGenEn-
ChkCap- ChkEn-
Kernel driver in use: sky2
Kernel modules: sky2
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