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Tue, 14 Jul 2026 01:40:15 +0000 (GMT) Received: from sapthagiri.in.ibm.com (unknown [9.39.30.210]) by smtpav07.fra02v.mail.ibm.com (Postfix) with ESMTP; Tue, 14 Jul 2026 01:40:15 +0000 (GMT) From: Srikar Dronamraju To: LKML , netdev@vger.kernel.org, David S Miller Cc: Ingo Molnar , Peter Zijlstra , Dietmar Eggemann , Dust Li , D Wythe , Eric Dumazet , Jakub Kicinski , Jon Maloy , Kuniyuki Iwashima , linux-sctp@vger.kernel.org, Mahanta Jambigi , Marcelo Ricardo Leitner , Paolo Abeni , Sidraya Jayagond , Simon Horman , Tony Lu , Wen Gu , Wenjia Zhang , Willem de Bruijn , Xin Long , Shrikanth Hegde , Vincent Guittot , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , K Prateek Nayak , Srikar Dronamraju Subject: [PATCH 0/2] net: Use synchronous wakeups selectively Date: Tue, 14 Jul 2026 07:09:41 +0530 Message-ID: <20260714013940.4068189-4-srikar@linux.ibm.com> X-Mailer: git-send-email 2.54.0 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-ORIG-GUID: swnZ8k84VhCHp9l1OgXmsrnlbZJyqjdA X-Proofpoint-Spam-Info: AW1haW4tMjYwNzE0MDAxMCBTYWx0ZWRfXwQeVNoERtGRG NDkywHfp3cFgJAW701EblrT5EmGFEkEWyIbb2XlNWpp6SDgsb8YNCi2ZbNVcyjGAy9QBrh9+9lB sx2kDnRcz99LD0Vozu4gLxzknEiVnbU= X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzE0MDAxMCBTYWx0ZWRfX0l+9M9RCV7/l SN13QSfmHhH5xXZllrrCXAbJEM7cXmUo4ShlwOhCVve+fG9nGsHeLGf8nYZeHfGiyEF9NkR0qWS 19+VOzvPzk9lEpvzk+kAyFRPo0YPgZkoLSiRt0l7822dT5TXvfTa78PGPDBkyMe8+7JG5oQfdhl ym/PfAH8beOsLYCK9XujKgPcQFZ+o14D/CnHiZ/JbOuDYcwVOSTLcF5tkzcYTJ6BhfGXhxdOng3 DURIIt0+r1Y7PJ9sRjkZXxN9961lPuM0m8nIc3/8zigFRPDuCLYb0vIUO3MciJeWKpOoZeSfhl3 f8hcpgreHM2zJZI58IquDQINu+uuy4HQTDEfiFc1NPIdXuSekryi1Jtjgc39D4/28PXhNkzz30c DRKO5YidoYlGuNEcDEYiIVYV/8bbTHA4/b9LmDJieGjv7WMAjZy+d1Jn/dlCCg2nYH8bsnxl6PF 7mzmostWJxz9tHolrmQ== X-Authority-Analysis: v=2.4 cv=IqMutr/g c=1 sm=1 tr=0 ts=6a55938d cx=c_pps a=bLidbwmWQ0KltjZqbj+ezA==:117 a=bLidbwmWQ0KltjZqbj+ezA==:17 a=RAioF0-LDSMA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=U7nrCbtTmkRpXpFmAIza:22 a=VuoEQsLsQp_es4t_5JUA:9 X-Proofpoint-GUID: ojGUtRFKMUJUAfLl9ciMPh-HwXf1RELn 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=2026-07-13_06,2026-07-10_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 clxscore=1011 impostorscore=0 malwarescore=0 adultscore=0 phishscore=0 suspectscore=0 priorityscore=1501 bulkscore=0 lowpriorityscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607140010 The scheduler assumes in several wakeup paths that a task using WF_SYNC is likely to yield the CPU shortly. However several networking wakeup paths unconditionally use synchronous wakeups even when the waking task continues execution. During wakeup, with WF_SYNC flag set, because of the assumption that current thread is ready to give up, the wakee thread will be migrated from any core within the chip to the current LLC. If these operations are frequent, and wakers are actually not going away, then it will lead to load imbalance and hurt performance. This is especially true in architectures where LLCs are small and number of LLCs per chip are more. Running vllm workload was run on Power10 system No patch with patch %diff Inference Time (sec) 17.84 16.35 -8.35% llm query bandwidth (tokens/sec) 14.78 16.21 +9.68% Lower inference time and higher tokens/sec is better. Srikar Dronamraju (2): net/socket: Record preference for synchronous wakeups net/sock: Propagate WF_SYNC only when requested include/net/sock.h | 1 + net/core/sock.c | 31 +++++++++++++++++++------ net/sctp/socket.c | 10 +++++++-- net/smc/af_smc.c | 4 ++-- net/smc/smc_rx.c | 10 +++++++-- net/socket.c | 56 +++++++++++++++++++++++++++++++++++++++------- net/tipc/socket.c | 22 +++++++++++++----- net/unix/af_unix.c | 26 ++++++++++++++------- 8 files changed, 126 insertions(+), 34 deletions(-) -- 2.51.0