0 Replies Latest reply: Apr 8, 2012 12:58 PM by JFFulcrum RSS

Chimney offload support in Intel SB`s

JFFulcrum Community Member
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Is integrated MAC-controller in current southbridges of 6-7 series chipsets possess MS Chimney-capable offloading capabilities? Chimney offloading is disabled in 'client' MS OSes by default, you can enable it manually via netsh commands, but seems like Intel hardware is incapable with this technology. Looking at DX79SI, current Intel top entusiast MB, in Windows 7 x64 with 17.0 network software by netsh interface tcp show chimneystat

 

Idx  Supp  Atmpt    TMax    PMax     Olc              Failure Reason
---  ----  -----    ----    ----     ---              --------------
12    No  -n/a-       0       0       0                       -n/a-
15    No  -n/a-       0       0       0                       -n/a-
13    No  -n/a-       0       0       0                       -n/a-
16    No  -n/a-       0       0       0                       -n/a-

 

12&16 is onboard Intel Ethernet adapters. Don`t mess with second adapter (16), cause 82574L is a cheap singlechip 'added value' controller, but primary adapter is a 82579 PHY combined with integrated chipset MAC, according to MB datasheet. Take a deeper look with netsh interface tcp show chimneystat 12

 

TCP Chimney Statistics for - INTERNET
---------------------------------------------------------
Interface Index                           : 12
Supports IPv4 connection offload          : No
Supports IPv6 connection offload          : No
Attempted to offload connections          : -n/a-
Some TCP settings denied by the NIC       : -n/a-
NIC denied connection offload request     : -n/a-
Offload capacity advertised by the NIC    : 0 connections
Offload Capacity Observed by the system   : 0 connections
Number of currently offloaded connections : 0
Successive offload attempt failures       : 0
Reason why last attempt to offload failed : -n/a-

 

So, no offloading. But we have clicked so many funny named 'offloading' options in network adapter properties! Well, their presence can be watched by different command,  netsh interface ipv4 show offload 12

 

Interface 12: INTERNET

ipv4 transmit checksum supported.
udp transmit checksum supported.
tcp transmit checksum supported.
tcp giant send offload supported.
ipv4 receive checksum supported.
udp receive checksum supported.
tcp receive checksum supported.

 

Not bad, but this is actually way older technology called 'Task offload' from Win2000, not as effective as Chimney.

 

So, is this lack of driver support, or support is absent in desktop chipsets at all? Second is not very good, cause NVIDIA nForce chipsets WAS capable for Chimney, at least for a while (NF4 series if i remember correctly). Of course, there are reasons for such cut-off, because in Vista times advanced offloading was erratic at best, but in Seven things was fixed, and most troubles came from NetDMA/DirectCache offloading techniques, which now are deprecated.

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