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Thu, 23 Jul 2026 08:50:07 +0000 (GMT) Received: from linux.ibm.com (unknown [9.126.150.29]) by smtpav05.fra02v.mail.ibm.com (Postfix) with ESMTP; Thu, 23 Jul 2026 08:50:07 +0000 (GMT) Date: Thu, 23 Jul 2026 14:19:56 +0530 From: Srikar Dronamraju To: Eric Dumazet Cc: Jakub Kicinski , LKML , netdev@vger.kernel.org, David S Miller , Ingo Molnar , Peter Zijlstra , Dietmar Eggemann , Dust Li , D Wythe , 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 Subject: Re: [PATCH 0/2] net: Use synchronous wakeups selectively Message-ID: Reply-To: Srikar Dronamraju References: <20260714013940.4068189-4-srikar@linux.ibm.com> <20260722100842.602fd5d2@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-ORIG-GUID: BDBsCyZq3H0b3cjmSqe402FANmvFSrr- X-Authority-Analysis: v=2.4 cv=V6RNF+ni c=1 sm=1 tr=0 ts=6a61d5cd cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=IkcTkHD0fZMA:10 a=RAioF0-LDSMA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=U7nrCbtTmkRpXpFmAIza:22 a=VwQbUJbxAAAA:8 a=1XWaLZrsAAAA:8 a=MzLsWxuSgiCLPq6Zp1UA:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 X-Proofpoint-Spam-Info: AW1haW4tMjYwNzIzMDA4NiBTYWx0ZWRfX8bmdL9T5rglM afa4O3H1pSJfQYvDGVhYQKt56tyemfuy63ar65DM9hzaDktMFWQeuLDPBUhwNvLN2zGmgpgClmI NgRWNA3yCT81dUS6T4ngZeR6l8X8hBg= X-Proofpoint-GUID: N9IEK1XpunVUWSBMyGEX440vpQlrKU-_ X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzIzMDA4NiBTYWx0ZWRfX3EBHpXRd66XD 4bXWGFkCSZqBkMFRMgFiw1dl51nFRr6SY9bqXT3Tp0zlI7Eb4640s5Wffy042foWoQPCpjFEWgZ XXm9NxWFgUQZO7o9hKc5kZDnW4q0oljpVrF5Bolg/WC0aa9CTisDMvrONlmyJZUOxiA0QSfMY4e G9fGgwKbzr7HwzA2FCW1UmeT5TLsSDjs1q7+sjxrNr3HivfhJEHOgYRVAv8AQLpjZXYCXoP/98h CNGRSUu6JDxNu8QFBhhnrq83dU0WkrbbKlIE8N+/j+BsOXrL8RwYyolO+wWs8wFp1J3Z+lc5lju WEHPlOA+ORuP5K8vVQJuPlQ+c7HWcijyT340tEeqb2w74RPEZhytN6yqSPmmdJr/mCJsB+nRCy9 9WJ0cayk8xNH7mt2xtE41ATh74HTmsRFU8uY2XV5b27EaGpdw+SOYi84NZVysZcYKNXHhuAIxwH gYT24WToU/Pu2tJf3gA== 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=2026-07-23_02,2026-07-22_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 adultscore=0 bulkscore=0 lowpriorityscore=0 clxscore=1015 spamscore=0 impostorscore=0 phishscore=0 priorityscore=1501 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607230086 * Eric Dumazet [2026-07-23 05:17:08]: > On Wed, Jul 22, 2026 at 7:08 PM Jakub Kicinski wrote: > > > > On Tue, 14 Jul 2026 07:09:41 +0530 Srikar Dronamraju wrote: > > > 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. > > > > Somewhat related recent patch: > > > > https://lore.kernel.org/all/20260708133815.3419465-1-usama.arif@linux.dev/ > > > > Maybe other maintainers will chime in, but I'm not convinced > > by the heuristics you're adding. The behavior will be workload > > specific. The extent of networking involvement should be letting > > the scheduler know that we're waking from IO, not leaking scheduler > > heuristics into networking. > > -- > > pw-bot: cr > > In any case, adding code to the fast path in every network system call > is undesirable. Yes, I understand adding code in fast path is undesirable. However as mentioned previous reply, we need to differentiate between blocking and non-blocking API. Doing unconditional nonblocking, is probably even worse. -- Thanks and Regards Srikar Dronamraju