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Sat, 6 Nov 2021 12:45:39 +0000 (GMT) Received: from [9.145.174.141] (unknown [9.145.174.141]) by d06av23.portsmouth.uk.ibm.com (Postfix) with ESMTP; Sat, 6 Nov 2021 12:45:39 +0000 (GMT) Message-ID: <8445f69e-54e6-0c54-a2de-0560cbf0e6ce@linux.ibm.com> Date: Sat, 6 Nov 2021 13:46:00 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.2.1 Subject: Re: [PATCH net 1/4] Revert "net/smc: don't wait for send buffer space when data was already sent" Content-Language: en-US To: Tony Lu Cc: Jakub Kicinski , davem@davemloft.net, netdev@vger.kernel.org, linux-s390@vger.kernel.org, linux-rdma@vger.kernel.org, jacob.qi@linux.alibaba.com, xuanzhuo@linux.alibaba.com, guwen@linux.alibaba.com, dust.li@linux.alibaba.com References: <20211027085208.16048-1-tonylu@linux.alibaba.com> <20211027085208.16048-2-tonylu@linux.alibaba.com> <9bbd05ac-5fa5-7d7a-fe69-e7e072ccd1ab@linux.ibm.com> <20211027080813.238b82ce@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> <06ae0731-0b9b-a70d-6479-de6fe691e25d@linux.ibm.com> <20211027084710.1f4a4ff1@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> <20211028073827.421a68d7@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> From: Karsten Graul Organization: IBM Deutschland Research & Development GmbH In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: ikKJlSI1m7-smd4oBKs2w62RZ0OsrB1h X-Proofpoint-GUID: LIgrbCnPsI5ThBkVrkktc0mqnAn0UyAQ X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.790,Hydra:6.0.425,FMLib:17.0.607.475 definitions=2021-11-06_02,2021-11-03_01,2020-04-07_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxscore=0 adultscore=0 spamscore=0 bulkscore=0 mlxlogscore=999 malwarescore=0 phishscore=0 impostorscore=0 clxscore=1015 lowpriorityscore=0 suspectscore=0 priorityscore=1501 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2110150000 definitions=main-2111060077 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 03/11/2021 04:06, Tony Lu wrote: > > I agree with you. I am curious about this deadlock scene. If it was > convenient, could you provide a reproducible test case? We are also > setting up a SMC CI/CD system to find the compatible and performance > fallback problems. Maybe we could do something to make it better. Run an echo server that uses blocking sockets. First call recv() with an 1MB buffer and when recv() returns then send all received bytes back to the client, no matter how many bytes where received. Run this in a loop (recv / send). On the client side also use only blocking sockets and a send / recv loop. Use an 1MB data buffer and call send() with the whole 1MB of data. Now run that with both scenarios (send() returns lesser bytes than requested vs. not).