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Wythe" Cc: dust.li@linux.alibaba.com, kuba@kernel.org, davem@davemloft.net, netdev@vger.kernel.org, linux-s390@vger.kernel.org, linux-rdma@vger.kernel.org References: <1641301961-59331-1-git-send-email-alibuda@linux.alibaba.com> <8a60dabb-1799-316c-80b5-14c920fe98ab@linux.ibm.com> <20220105044049.GA107642@e02h04389.eu6sqa> <20220105085748.GD31579@linux.alibaba.com> <20220105150612.GA75522@e02h04389.eu6sqa> From: Karsten Graul Organization: IBM Deutschland Research & Development GmbH In-Reply-To: <20220105150612.GA75522@e02h04389.eu6sqa> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: Ht9CE45YnXG5lb09FAey3s1bPxafW6N9 X-Proofpoint-ORIG-GUID: iL_dZu0klVtlWvci52WsqiW8gJGxpyKO X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.790,Hydra:6.0.425,FMLib:17.11.62.513 definitions=2022-01-05_05,2022-01-04_01,2021-12-02_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 malwarescore=0 impostorscore=0 priorityscore=1501 mlxscore=0 bulkscore=0 lowpriorityscore=0 suspectscore=0 spamscore=0 mlxlogscore=999 adultscore=0 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2110150000 definitions=main-2201050123 Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org On 05/01/2022 16:06, D. Wythe wrote: > LGTM. Fallback makes the restrictions on SMC dangling > connections more meaningful to me, compared to dropping them. > > Overall, i see there are two scenario. > > 1. Drop the overflow connections limited by userspace application > accept. > > 2. Fallback the overflow connections limited by the heavy process of > current SMC handshake. ( We can also control its behavior through > sysctl.) > I vote for (2) which makes the behavior from user space applications point of view more like TCP. One comment to sysctl: our current approach is to add new switches to the existing netlink interface which can be used with the smc-tools package (or own implementations of course). Is this prereq problematic in your environment? We tried to avoid more sysctls and the netlink interface keeps use more flexible.