Re: How to verify multichannel

["Aurélien Aptel" <aaptel@suse.com>]

Xiaoli Feng <xifeng@redhat.com> writes:
> Now I can see the multiple channel info in network package when mount with
> option "max_channel=2". If doesn't specify it. Client will only open one 
> channel.

That's correct.

> And my smb.conf setup below can work for multichannel. Seems server
> and client don't require multiple network interfaces. And also don't need 
> network team.

The client will try to reuse the same server interface if it has the RSS
capability flag set.

https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-smb2/fcd862d1-1b85-42df-92b1-e103199f531f

RSS flag means that this server interface can handle things in parallel
efficiently.

> But When test seedup, it isn't change. I use two vm in the same host. And
> each have 4 cpu and 1G memory. Maybe it's the problem.

Maybe the problem is not the number of CPU but the virtual network bus
bandwidth.

Let me explain: forget SMB and measure network speed (with iperf)
between 2 VMs. Let's say you get 1GB/s.

Now you add a virtual interface to the server VM and measure again on the 2
interfaces *at the same time*. You will see at most 500MB/s on each.

If you want to measure speedup, you need to limit the bandwidth of the
server interfaces with tc so that when you max out the server interface
bandwidth, you don't also max out the total virtual bus bandwidth.
If you limit 1MB/s on each, 1+1 = 2MB/s which is still << 1GB/s but you
will get speedup of 2.

> Thanks so much.

No problem :)

Cheers,
-- 
Aurélien Aptel / SUSE Labs Samba Team
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