Re: [PATCH net-next v6 00/11] net/smc: SMC intra-OS shortcut with loopback-ism

Jan Karcher
2024-04-26T07:03:06Z

On 14/04/2024 06:02, 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.
>
> - Design
>
> This patch set includes 3 parts:
>
> - Patch #1: some prepare work for loopback-ism.
> - Patch #2-#7: implement loopback-ism device and adapt SMC-D for it.
> loopback-ism now serves only SMC and no userspace interfaces exposed.
> - Patch #8-#11: memory copy optimization for intra-OS scenario.
>
> The loopback-ism device is designed as an ISMv2 device and not be limited to
> a specific net namespace, ends of both inter-process connection (1/1' in diagram
> below) or inter-container connection (2/2' in diagram below) can find the same
> available loopback-ism and choose it during the CLC handshake.
>
> Container 1 (ns1) Container 2 (ns2)
> +-----------------------------------------+ +-------------------------+
> | +-------+ +-------+ +-------+ | | +-------+ |
> | | App A | | App B | | App C | | | | App D |<-+ |
> | +-------+ +---^---+ +-------+ | | +-------+ |(2') |
> | |127.0.0.1 (1')| |192.168.0.11 192.168.0.12| |
> | (1)| +--------+ | +--------+ |(2) | | +--------+ +--------+ |
> | `-->| lo |-` | eth0 |<-` | | | lo | | eth0 | |
> +---------+--|---^-+---+-----|--+---------+ +-+--------+---+-^------+-+
> | | | |
> Kernel | | | |
> +----+-------v---+-----------v----------------------------------+---+----+
> | | TCP | |
> | | | |
> | +--------------------------------------------------------------+ |
> | |
> | +--------------+ |
> | | smc loopback | |
> +---------------------------+--------------+-----------------------------+
>
> loopback-ism device creates DMBs (shared memory) for each connection peer.
> Since data transfer occurs within the same kernel, the sndbuf of each peer
> is only a descriptor and point to the same memory region as peer DMB, so that
> the data copy from sndbuf to peer DMB can be avoided in loopback-ism case.
>
> Container 1 (ns1) Container 2 (ns2)
> +-----------------------------------------+ +-------------------------+
> | +-------+ | | +-------+ |
> | | App C |-----+ | | | App D | |
> | +-------+ | | | +-^-----+ |
> | | | | | |
> | (2) | | | (2') | |
> | | | | | |
> +---------------|-------------------------+ +----------|--------------+
> | |
> Kernel | |
> +---------------|-----------------------------------------|--------------+
> | +--------+ +--v-----+ +--------+ +--------+ |
> | |dmb_desc| |snd_desc| |dmb_desc| |snd_desc| |
> | +-----|--+ +--|-----+ +-----|--+ +--------+ |
> | +-----|--+ | +-----|--+ |
> | | DMB C | +---------------------------------| DMB D | |
> | +--------+ +--------+ |
> | |
> | +--------------+ |
> | | smc loopback | |
> +---------------------------+--------------+-----------------------------+
>
> - Benchmark Test
>
> * Test environments:
> - VM with Intel Xeon Platinum 8 core 2.50GHz, 16 GiB mem.
> - SMC sndbuf/DMB size 1MB.
>
> * Test object:
> - TCP: run on TCP loopback.
> - SMC lo: run on SMC loopback-ism.
>
> 1. ipc-benchmark (see [3])
>
> - ./<foo> -c 1000000 -s 100
>
> TCP SMC-lo
> Message
> rate (msg/s) 79693 148236(+86.01%)
>
> 2. sockperf
>
> - serv: <smc_run> sockperf sr --tcp
> - clnt: <smc_run> sockperf { tp | pp } --tcp --msg-size={ 64000 for tp | 14 for pp } -i 127.0.0.1 -t 30
>
> TCP SMC-lo
> Bandwidth(MBps) 4815.18 8061.77(+67.42%)
> Latency(us) 6.176 3.449(-44.15%)
>
> 3. nginx/wrk
>
> - serv: <smc_run> nginx
> - clnt: <smc_run> wrk -t 8 -c 1000 -d 30 http://127.0.0.1:80
>
> TCP SMC-lo
> Requests/s 196555.02 263270.95(+33.94%)
>
> 4. redis-benchmark
>
> - serv: <smc_run> redis-server
> - clnt: <smc_run> redis-benchmark -h 127.0.0.1 -q -t set,get -n 400000 -c 200 -d 1024
>
> TCP SMC-lo
> GET(Requests/s) 88711.47 120048.02(+35.32%)
> SET(Requests/s) 89465.44 123152.71(+37.65%)
>
>

Hi Wen Gu,

I did run the tests again with the v6 and reviewed the patchset. If you
decide to address Simons nit feel free to add my:

Reviewed-and-tested-by: Jan Karcher <jaka@linux.ibm.com>

Thanks for your effort and contribution.
- J