Re: [LSF/MM/BPF TOPIC] NVMe over MPTCP: Multi-Fold Acceleration for NVMe over TCP in Multi-NIC Environments

[Geliang Tang <geliang@kernel.org>]

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Hello everyone,

Thank you for your interest in NVMe over MPTCP. I have attached the
slides from the presentation to this email.

Please note that the demo in the slides only configured a single NVMe
multipath. Subsequently, I will post the MPTCP performance test results
under several NVMe multipaths here.

Thanks,
-Geliang

On Thu, 2026-03-05 at 12:30 +0800, Geliang Tang wrote:
> Hi Nilay, Ming,
> 
> Thank you again for your interest in NVMe over MPTCP.
> 
> On Thu, 2026-02-26 at 17:54 +0800, Geliang Tang wrote:
> > Hi Nilay,
> > 
> > Thanks for your reply.
> > 
> > On Wed, 2026-02-25 at 20:37 +0530, Nilay Shroff wrote:
> > > 
> > > 
> > > On 1/29/26 9:43 AM, Geliang Tang wrote:
> > > > 3. Performance Benefits
> > > > 
> > > > This new feature has been evaluated in different environments:
> > > > 
> > > > I conducted 'NVMe over MPTCP' tests between two PCs, each
> > > > equipped
> > > > with
> > > > two Gigabit NICs and directly connected via Ethernet cables.
> > > > Using
> > > > 'NVMe over TCP', the fio benchmark showed a speed of
> > > > approximately
> > > > 100
> > > > MiB/s. In contrast, 'NVMe over MPTCP' achieved about 200 MiB/s
> > > > with
> > > > fio, doubling the throughput.
> > > > 
> > > > In a virtual machine test environment simulating four NICs on
> > > > both
> > > > sides, 'NVMe over MPTCP' delivered bandwidth up to four times
> > > > that
> > > > of
> > > > standard TCP.
> > > 
> > > This is interesting. Did you try using an NVMe multipath iopolicy
> > > other
> > > than the default numa policy? Assuming both the host and target
> > > are
> > > multihomed,
> > > configuring round-robin or queue-depth may provide performance
> > > comparable
> > > to what you are seeing with MPTCP.
> > > 
> > > I think MPTCP shall distribute traffic using transport-level
> > > metrics
> > > such as
> > > RTT, cwnd, and packet loss, whereas the NVMe multipath layer
> > > makes
> > > decisions
> > > based on ANA state, queue depth, and NUMA locality. In a setup
> > > with
> > > multiple
> > > active paths, switching the iopolicy from numa to round-robin or
> > > queue-depth
> > > could improve load distribution across controllers and thus
> > > improve
> > > performance.
> > > 
> > > IMO, it would be useful to test with those policies and compare
> > > the
> > > results
> > > against the MPTCP setup.
> > 
> > Ming Lei also made a similar comment. In my experiments, I didn't
> > set
> > the multipath iopolicy, so I was using the default numa policy. In
> > the
> > follow-up, I'll adjust it to round-robin or queue-depth and rerun
> > the
> > experiments. I'll share the results in this email thread.
> 
> Based on your feedback, I have added iopolicy support to the NVMe
> over
> MPTCP selftest script (see patch 8 in [1]). We can set the iopolicy
> to
> round-robin like this:
> 
>  # ./mptcp_nvme.sh mptcp round-robin
> 
> This demonstrates that "NVMe over MPTCP" and "NVMe multipath" can
> work
> simultaneously without conflict.
> 
> Using this test script, I compared three I/O policies: numa, round-
> robin, and queue-depth. The results for fio were very similar. It's
> possible that this test environment doesn't fully reflect the
> differences in I/O policies. I will continue to follow up with
> further
> tests.
> 
> Thanks,
> -Geliang
> 
> [1]
> NVME over MPTCP, v4
> https://patchwork.kernel.org/project/mptcp/cover/cover.1772683110.git.tanggeliang@kylinos.cn/
> 
> > 
> > Thanks,
> > -Geliang
> > 
> > > 
> > > Thanks,
> > > --Nilay


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