Re: [PATCH net-next v7 00/11] net/smc: SMC intra-OS shortcut with loopback-ism

From: Cong Wang <xiyou.wangcong@gmail.com>
To: Wen Gu <guwen@linux.alibaba.com>
Cc: wintera@linux.ibm.com, twinkler@linux.ibm.com, hca@linux.ibm.com,
	gor@linux.ibm.com, agordeev@linux.ibm.com, davem@davemloft.net,
	edumazet@google.com, kuba@kernel.org, pabeni@redhat.com,
	wenjia@linux.ibm.com, jaka@linux.ibm.com,
	borntraeger@linux.ibm.com, svens@linux.ibm.com,
	alibuda@linux.alibaba.com, tonylu@linux.alibaba.com,
	linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org,
	netdev@vger.kernel.org, bpf@vger.kernel.org
Subject: Re: [PATCH net-next v7 00/11] net/smc: SMC intra-OS shortcut with loopback-ism
Date: Sun, 28 Apr 2024 08:49:54 -0700	[thread overview]
Message-ID: <Zi5wIrf3nAeJh1u5@pop-os.localdomain> (raw)
In-Reply-To: <20240428060738.60843-1-guwen@linux.alibaba.com>

On Sun, Apr 28, 2024 at 02:07:27PM +0800, Wen Gu wrote:
> This patch set acts as the second part of the new version of [1] (The first
> part can be referred from [2]), the updated things of this version are listed
> at the end.
> 
> - Background
> 
> SMC-D is now used in IBM z with ISM function to optimize network interconnect
> for intra-CPC communications. Inspired by this, we try to make SMC-D available
> on the non-s390 architecture through a software-implemented Emulated-ISM device,
> that is the loopback-ism device here, to accelerate inter-process or
> inter-containers communication within the same OS instance.

Just FYI:

Cilium has implemented this kind of shortcut with sockmap and sockops.
In fact, for intra-OS case, it is _very_ simple. The core code is less
than 50 lines. Please take a look here:
https://github.com/cilium/cilium/blob/v1.11.4/bpf/sockops/bpf_sockops.c

Like I mentioned in my LSF/MM/BPF proposal, we plan to implement
similiar eBPF things for inter-OS (aka VM) case.

More importantly, even LD_PRELOAD is not needed for this eBPF approach.
:)

Thanks.