Hello,
I've recently bought Realtek RTL8169S-32 chip based Gigabit Ethernet card:
# lspci -vv
Ethernet controller: Realtek Semiconductor Co., Ltd. RTL-8169 Gigabit
Ethernet (rev 10)
Subsystem: Realtek Semiconductor Co., Ltd. RTL-8169 Gigabit
Ethernet
Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV+ VGASnoop-
ParErr- Stepping- SERR+ FastB2B-
Status: Cap+ 66MHz+ UDF- FastB2B+ ParErr- DEVSEL=medium
>TAbort- <TAbort- <MAbort- >SERR- <PERR-
Latency: 64 (8000ns min, 16000ns max), Cache Line Size 20
Interrupt: pin A routed to IRQ 10
Region 0: I/O ports at c400 [size=256]
Region 1: Memory at fe9fec00 (32-bit, non-prefetchable) [size=256]
Expansion ROM at fe9c0000 [disabled] [size=128K]
Capabilities: [dc] Power Management version 2
Flags: PMEClk- DSI- D1+ D2+ AuxCurrent=375mA
PME(D0-,D1+,D2+,D3hot+,D3cold+)
Status: D0 PME-Enable- DSel=0 DScale=0 PME-
I've noticed that all TX offload features (tx-checksumming,
scatter-gather and TSO) are disabled by default and should be manually
enabled by ethtool. I wonder, is there any particular reason for that?
Why they are not enabled by default as it was done for e1000 or tg3? Are
there any hidden drawbacks in enabling them?
Those offload options are definitely work. They give in my setup (32-bit
66MHz PCI, Xeon 1.7GHz CPU, open-iscsi) CPU offload from 75% to 45% and
data write throughput improvement from 55MB/s to 59MB/s.
Regards,
Vlad
(please remove l-k from the Cc:, this ought to be sent to netdev)
Vladislav Bolkhovitin <[email protected]> :
>
> I've recently bought Realtek RTL8169S-32 chip based Gigabit Ethernet card:
>
> # lspci -vv
[...]
> I've noticed that all TX offload features (tx-checksumming,
> scatter-gather and TSO) are disabled by default and should be manually
> enabled by ethtool. I wonder, is there any particular reason for that?
As far as I can tell, it is mostly a lack of pressure from the users and
my desire to avoid a change of behavior.
> Why they are not enabled by default as it was done for e1000 or tg3? Are
> there any hidden drawbacks in enabling them?
None that I know of. I had not noticed a huge difference and people did
not comment a lot either...
> Those offload options are definitely work. They give in my setup (32-bit
> 66MHz PCI, Xeon 1.7GHz CPU, open-iscsi) CPU offload from 75% to 45% and
> data write throughput improvement from 55MB/s to 59MB/s.
...but your datapoint is welcome.
--
Ueimor