From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D36C1107B9 for ; Tue, 26 Sep 2023 12:09:09 +0000 (UTC) Received: from out30-97.freemail.mail.aliyun.com (out30-97.freemail.mail.aliyun.com [115.124.30.97]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6DF89E6; Tue, 26 Sep 2023 05:09:07 -0700 (PDT) X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R721e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018045192;MF=dust.li@linux.alibaba.com;NM=1;PH=DS;RN=18;SR=0;TI=SMTPD_---0VswpDWa_1695730143; Received: from localhost(mailfrom:dust.li@linux.alibaba.com fp:SMTPD_---0VswpDWa_1695730143) by smtp.aliyun-inc.com; Tue, 26 Sep 2023 20:09:04 +0800 Date: Tue, 26 Sep 2023 20:09:03 +0800 From: Dust Li To: Leon Romanovsky , Alexandra Winter Cc: Albert Huang , Karsten Graul , Wenjia Zhang , Jan Karcher , "D. Wythe" , Tony Lu , Wen Gu , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , linux-s390@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, RDMA mailing list , Jason Gunthorpe Subject: Re: [PATCH net-next] net/smc: add support for netdevice in containers. Message-ID: <20230926120903.GD92403@linux.alibaba.com> Reply-To: dust.li@linux.alibaba.com References: <20230925023546.9964-1-huangjie.albert@bytedance.com> <20230926104831.GJ1642130@unreal> <76a74084-a900-d559-1f63-deff84e5848a@linux.ibm.com> <20230926114104.GL1642130@unreal> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230926114104.GL1642130@unreal> X-Spam-Status: No, score=-9.9 required=5.0 tests=BAYES_00, ENV_AND_HDR_SPF_MATCH,RCVD_IN_DNSWL_BLOCKED,SPF_HELO_NONE,SPF_PASS, UNPARSEABLE_RELAY,USER_IN_DEF_SPF_WL autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net On Tue, Sep 26, 2023 at 02:41:04PM +0300, Leon Romanovsky wrote: >On Tue, Sep 26, 2023 at 01:14:04PM +0200, Alexandra Winter wrote: >> >> >> On 26.09.23 12:48, Leon Romanovsky wrote: >> > This patch made me wonder, why doesn't SMC use RDMA-CM like all other >> > in-kernel ULPs which work over RDMA? >> > >> > Thanks >> >> The idea behind SMC is that it should look an feel to the applications >> like TCP sockets. So for connection management it uses TCP over IP; >> RDMA is just used for the data transfer. > >I think that it is not different from other ULPs. For example, RDS works >over sockets and doesn't touch or reimplement GID management logic. I think the difference is SMC socket need to be compatible with TCP socket, so it need a tcp socket to fallback when something is not working. If SMC works with rdmacm, it still need a fallback-to-tcp socket, and the tcp connection has to be established for each SMC socket before the SMC socket got established, that would make rdmacm meaningless. Best regards, Dust > >Thanks