samba - Sep 2016 - No increased throughput with SMB Multichannel and two NICs

Hello,

I'm running Samba 4.4.5 with enabled SMB Multichannel. The Linux server
has two 1GBit/s NICs and for testing purposes I've shared a tmpfs
mountpoint with 2GiB and ~2GiB large test-file.

My Windows 10 host has one dual-port 1GBit/s NIC, and if both interfaces
are enabled, Get-SmbMultichannelConnection lists active multichannel
connections to my Linux SMB server.

If I disable one NIC on Windows, the other NIC is used with ~1GBit/s
when transferring the test-file from Linux to Windows.
If I enable both NICs, instead of 2x1Gbit/s I only get ~500MBit/s per
interface (but both interfaces are used).

So instead of doubling the throughput, traffic is split up between two
interface half by half.

Is it possible to change this behaviour?


Hardware infos on Linux:

07:00.0 Ethernet controller: Intel Corporation I210 Gigabit Network
Connection (rev 03)
08:00.0 Ethernet controller: Intel Corporation I210 Gigabit Network
Connection (rev 03)

# uname -a
Linux mz4 3.16.0-4-amd64 #1 SMP Debian 3.16.7-ckt25-2+deb8u3
(2016-07-02) x86_64 GNU/Linux

/# /usr/local/samba/sbin/smbd --version
Version 4.4.5

Hardware infos on Windows 10:
Intel PRO/1000 PT Dual Port Server Adapter



Regards,
Daniel Vogelbacher

On Sun, 2016-09-04 at 11:42 +0200, Daniel Vogelbacher via samba
wrote:
> Hello,
> 
> I'm running Samba 4.4.5 with enabled SMB Multichannel. The Linux
> server
> has two 1GBit/s NICs and for testing purposes I've shared a tmpfs
> mountpoint with 2GiB and ~2GiB large test-file.
> 
> My Windows 10 host has one dual-port 1GBit/s NIC, and if both
> interfaces
> are enabled, Get-SmbMultichannelConnection lists active multichannel
> connections to my Linux SMB server.
> 
> If I disable one NIC on Windows, the other NIC is used with ~1GBit/s
> when transferring the test-file from Linux to Windows.
> If I enable both NICs, instead of 2x1Gbit/s I only get ~500MBit/s per
> interface (but both interfaces are used).
> 
> So instead of doubling the throughput, traffic is split up between
> two
> interface half by half.
> 
This is mostly a Windows client-controlled behavior. Refer to the
following reply for a thread on similar subject for more details. 

https://lists.samba.org/archive/samba/2016-August/201841.html

> Is it possible to change this behaviour?
> 
> 
> Hardware infos on Linux:
> 
> 07:00.0 Ethernet controller: Intel Corporation I210 Gigabit Network
> Connection (rev 03)
> 08:00.0 Ethernet controller: Intel Corporation I210 Gigabit Network
> Connection (rev 03)
> 
> # uname -a
> Linux mz4 3.16.0-4-amd64 #1 SMP Debian 3.16.7-ckt25-2+deb8u3
> (2016-07-02) x86_64 GNU/Linux
> 
> /# /usr/local/samba/sbin/smbd --version
> Version 4.4.5
> 
> Hardware infos on Windows 10:
> Intel PRO/1000 PT Dual Port Server Adapter
> 
> 
> 
> Regards,
> Daniel Vogelbacher
>

Am 2016-09-06 10:41, schrieb Anoop C S via samba:
> On Sun, 2016-09-04 at 11:42 +0200, Daniel Vogelbacher via samba wrote:
>> Hello,
>> 
>> I'm running Samba 4.4.5 with enabled SMB Multichannel. The Linux
>> server
>> has two 1GBit/s NICs and for testing purposes I've shared a tmpfs
>> mountpoint with 2GiB and ~2GiB large test-file.
>> 
>> My Windows 10 host has one dual-port 1GBit/s NIC, and if both
>> interfaces
>> are enabled, Get-SmbMultichannelConnection lists active multichannel
>> connections to my Linux SMB server.
>> 
>> If I disable one NIC on Windows, the other NIC is used with ~1GBit/s
>> when transferring the test-file from Linux to Windows.
>> If I enable both NICs, instead of 2x1Gbit/s I only get ~500MBit/s per
>> interface (but both interfaces are used).
>> 
>> So instead of doubling the throughput, traffic is split up between
>> two
>> interface half by half.
>> 
> 
> This is mostly a Windows client-controlled behavior. Refer to the
> following reply for a thread on similar subject for more details. 
> 
> https://lists.samba.org/archive/samba/2016-August/201841.html

[...]AFAIK, the windows client only puts traffic on interfaces of same
speed and quality simultaneouslt[...]

I interpret this as "with two identical NIC-speeds at server-side and 
client-side it should result in double throughput".
On both hosts I've 2x1GBit/s NICs and Windows uses both(!) NICs (but not 
at full speed when multichannel is enabled). So I don't think my problem 
is related to this thread, beacuse if it is, Windows would choose only 
one NIC.

>> Is it possible to change this behaviour?
>> 
>> 
>> Hardware infos on Linux:
>> 
>> 07:00.0 Ethernet controller: Intel Corporation I210 Gigabit Network
>> Connection (rev 03)
>> 08:00.0 Ethernet controller: Intel Corporation I210 Gigabit Network
>> Connection (rev 03)
>> 
>> # uname -a
>> Linux mz4 3.16.0-4-amd64 #1 SMP Debian 3.16.7-ckt25-2+deb8u3
>> (2016-07-02) x86_64 GNU/Linux
>> 
>> /# /usr/local/samba/sbin/smbd --version
>> Version 4.4.5
>> 
>> Hardware infos on Windows 10:
>> Intel PRO/1000 PT Dual Port Server Adapter
>> 
>> 
>> 
>> Regards,
>> Daniel Vogelbacher
>>