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Wythe" , wenjia@linux.ibm.com, wintera@linux.ibm.com, dust.li@linux.alibaba.com, tonylu@linux.alibaba.com, guwen@linux.alibaba.com Cc: kuba@kernel.org, davem@davemloft.net, netdev@vger.kernel.org, linux-s390@vger.kernel.org, linux-rdma@vger.kernel.org, leonro@nvidia.com, pabeni@redhat.com, edumazet@google.com, sidraya@linux.ibm.com, jaka@linux.ibm.com, oliver.yang@linux.alibaba.com References: <20260716113745.65234-1-alibuda@linux.alibaba.com> <20260716113745.65234-4-alibuda@linux.alibaba.com> <92ba5a37-3496-424c-8425-6535515c01ce@linux.ibm.com> Content-Language: en-US In-Reply-To: <92ba5a37-3496-424c-8425-6535515c01ce@linux.ibm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-Spam-Info: AW1haW4tMjYwNzMwMDAyNSBTYWx0ZWRfX/H5qKL6GcEn9 S6Nznmgr6saR34unq+hz2j32shsxN5OQwC/ym2E1p9OI3qwNyZ5EJEYU/XqAFL7h+iB1Ok7Qw8C NBXvpSatD9CBxU6L3peJmhlfIiRJbbY= X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzMwMDAyNSBTYWx0ZWRfX0INZglNAqDdA ytd5WEGLh0sZmB9mU8WjxddwCUNKMGsePkh5w+rhOJv7D0m+wJbLtPTOdEVBCJHU8OFKuRomber OM+4HqdmgT/alIinIcPfkrKeZJmHYdNh73Qnn+zW31G8Tk1LbUEXInPF4tjk6q5U2jb5VGqOPLo LKxDmsgTN8nwHA/arcpKWqRRsNXs1aS4/tvI23wY0GyQNJNbFss3gWnMi8X+mpRQTHpPeCSeInV G7NkdBJWf2GoTH1H2XlVdH0Rhnjd/l//Kgepo7M7Zfey9paMIAmTvBZUAZrkTWFpUlbzr6q8SRd 81umLZFeMHM/gjXxdyVvGN98mHALgliDGGSvSrRXSqPUG+uQvnMLotUgyRmHILlQVcaWJPVn9ox 6fPyuuHQam2n1/Pk6YkxzvFDQ584jPJYspEhCz1G8imAZrRQKj+AHBYnWwOqiw/SPh+fLUQW2PY l+5ySDiXNH2xLu4pLAg== X-Authority-Analysis: v=2.4 cv=b5WCJNGx c=1 sm=1 tr=0 ts=6a6ad757 cx=c_pps a=aDMHemPKRhS1OARIsFnwRA==:117 a=aDMHemPKRhS1OARIsFnwRA==:17 a=IkcTkHD0fZMA:10 a=RAioF0-LDSMA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=V8glGbnc2Ofi9Qvn3v5h:22 a=VwQbUJbxAAAA:8 a=SRrdq9N9AAAA:8 a=T4hTGduiKsk5PSsedNQA:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 X-Proofpoint-GUID: q1NC9aP8prvMCy73BgNFbv7Mm8lQjfo- X-Proofpoint-ORIG-GUID: 9_IQJPloFO6RIeZd73RkvClhUvAFdJMQ X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-07-30_01,2026-07-29_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 spamscore=0 adultscore=0 malwarescore=0 impostorscore=0 bulkscore=0 phishscore=0 suspectscore=0 clxscore=1015 lowpriorityscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607300025 On 22/07/26 5:17 pm, Mahanta Jambigi wrote: > > > On 16/07/26 5:07 pm, D. Wythe wrote: >> Performance Test: redis-benchmark with max 32 connections per QP >> Data format: Requests Per Second (RPS), Percentage in brackets >> represents the gain/loss compared to TCP. >> >> | Clients | TCP | SMC (original) | SMC (cq_pool) | >> |---------|----------|---------------------|---------------------| >> | c = 1 | 24449 | 31172 (+27%) | 34039 (+39%) | >> | c = 2 | 46420 | 53216 (+14%) | 64391 (+38%) | >> | c = 16 | 159673 | 83668 (-48%) <-- | 216947 (+36%) | >> | c = 32 | 164956 | 97631 (-41%) <-- | 249376 (+51%) | >> | c = 64 | 166322 | 118192 (-29%) <-- | 249488 (+50%) | >> | c = 128 | 167700 | 121497 (-27%) <-- | 249480 (+48%) | >> | c = 256 | 175021 | 146109 (-16%) <-- | 240384 (+37%) | >> | c = 512 | 168987 | 101479 (-40%) <-- | 226634 (+34%) | >> >> The results demonstrate that this optimization effectively resolves the >> scalability bottleneck, with RPS increasing by over 110% at c=64 >> compared to the original implementation. > > Thanks for the performance numbers — the scalability improvement at high > client counts is striking. A few questions to help reproduce these results: > > 1) Was net.smc.smcr_max_conns_per_lgr=32 the value used? The "max 32 > connections per QP" in the description suggests so, but the sysctl > wasn't explicitly listed. > > 2) Were net.smc.smcr_max_send_wr and net.smc.smcr_max_recv_wr left at > their defaults, or tuned? With per-link CQs the optimal WR counts may > differ from the global-CQ case, so knowing whether these were touched > would help interpret the numbers. > > 3) Was this SMC-R v2? The v2 TX path (smc_wr_tx_get_v2_slot, > wr_tx_v2_ib) has different concurrency characteristics, so confirming > the version matters for the contention analysis in patch 2/3 as well. > > 4) Was uperf tested for v4 as well, as we did for v1[1] in > February-2026? uperf exercises a wider range of message sizes and thread > counts, so its numbers would strengthen the case — particularly for the > intermediate client counts (c=16 to c=64) where the original > implementation regresses below TCP. @D. Wythe: Gentle reminder regarding my earlier questions. Have you had a chance to look into them? > > [1] > https://lore.kernel.org/netdev/20260202094800.30373-1-alibuda@linux.alibaba.com/