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Tue, 21 Jul 2026 04:31:49 +0000 (GMT) Received: from [9.39.17.99] (unknown [9.39.17.99]) by smtpav02.fra02v.mail.ibm.com (Postfix) with ESMTP; Tue, 21 Jul 2026 04:31:48 +0000 (GMT) Message-ID: Date: Tue, 21 Jul 2026 10:01:34 +0530 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v5 1/1] cpuhp: Expedite RCU when toggling system-wide SMT mode From: Shrikanth Hegde To: paulmck@kernel.org, tglx@linutronix.de, peterz@infradead.org, Ingo Molnar Cc: linux-kernel@vger.kernel.org, rcu@vger.kernel.org, aboorvad@linux.ibm.com, boqun.feng@gmail.com, frederic@kernel.org, joelagnelf@nvidia.com, josh@joshtriplett.org, neeraj.upadhyay@kernel.org, rostedt@goodmis.org, srikar@linux.ibm.com, urezki@gmail.com, Vishal Chourasia , samir@linux.ibm.com References: <20260615042514.694993-2-vishalc@linux.ibm.com> <20260615042514.694993-4-vishalc@linux.ibm.com> <4bd12c51-414d-49b5-8fce-2a6e73a479fa@linux.ibm.com> Content-Language: en-US In-Reply-To: <4bd12c51-414d-49b5-8fce-2a6e73a479fa@linux.ibm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Authority-Analysis: v=2.4 cv=HJXz0Itv c=1 sm=1 tr=0 ts=6a5ef63d cx=c_pps a=GFwsV6G8L6GxiO2Y/PsHdQ==:117 a=GFwsV6G8L6GxiO2Y/PsHdQ==:17 a=IkcTkHD0fZMA:10 a=RAioF0-LDSMA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=Y2IxJ9c9Rs8Kov3niI8_:22 a=VnNF1IyMAAAA:8 a=VwQbUJbxAAAA:8 a=ZqOttr7FMA8WdoUQ5m8A:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzIxMDA0MCBTYWx0ZWRfX5ZqvZl+SrCxZ 5ZNINNNKUCTCTTRiIFfPmbhEP9XysGCjSsqjmxF5VbRXOdktOxaafMFyfBoumQiJBl8rYPTM4Th sVqyhsIyCaLGHBXuzR+DScwRoU82F2M4Fqkp8rrzT/vSZ47gFwEadGbZT+nVt25emDmCz1aDsH0 8DqJD2a3OqLe3G4ILf3+Jdy+WzDk1pKU6GiuurUHIhOgrsJzw0oDKIAQovPIcUIqOVNYELZqBei NpgsfGln/2j1O5pN85x0nTEP64G+MbCfVEJwVEUjCQCgUR/dkNdX8Y5BC19Fhv6iI3vcExGZvda rr97SierZJ1xCULnhp5FlW597/pDD8UCRgC6YULG6VJMf4USE/aEntgXXBh/dfqrSCXMbXYsLNr MbWAE5cAnVgbJCYDJDBCmMJV2ou2YYEIG1T2b9acqmZ3aSHYqgReGqrK6UAHcRINhkJNfPCZKWs 8YIax6HbL3B4bUwOvjA== X-Proofpoint-ORIG-GUID: 4fFJY9S0K9nugp0_l1IW4-cDa9E-fFil X-Proofpoint-Spam-Info: AW1haW4tMjYwNzIxMDA0MCBTYWx0ZWRfX0oqp2t+m2FRD CWjTS96BnTg2/v/jsc2G7hHxo4TrxAhC0Csd80VxxXDxBTVIpeqDC1wW9zZ2IjbxN5ovElaWgXp f39iQO9yLhYs7pviiICY8oQOWD1umRY= X-Proofpoint-GUID: BxrJPxiLo3B26SGzZQmXiWpbnXUKsype 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=2026-07-20_06,2026-07-20_03,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 priorityscore=1501 lowpriorityscore=0 suspectscore=0 malwarescore=0 impostorscore=0 clxscore=1015 phishscore=0 spamscore=0 adultscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607210040 On 6/16/26 11:39 AM, Shrikanth Hegde wrote: > > >>> >>> On a large config system with 1920 CPUs, completion time improves from >>> ~1 hour to 5-6 minutes. >>> >>> Tested-by: Samir >>> Reviewed-by: Shrikanth Hegde >>> Signed-off-by: Vishal Chourasia >> >>  From an RCU viewpoint: >> >> Reviewed-by: Paul E. McKenney > > Thank you Paul for reviewing this. > >> >> I am guessing that you will be taking this up some other path, but if >> you would like it to to via RCU, please let me know. >> >>                             Thanx, Paul >> > > I would prefer this to go via tip tree since main change is in cpu.c > > Thomas, peter, > What do you guys suggest? can this go via tip tree? > > Also, do you have any other review comments on this or test to be done? > Gentle Ping. Thomas, Peter, Ingo, Can this go via tip tree? Do you guys have any comments to be addressed? Or Do you want it to go via RCU tree?