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Wed, 29 Jul 2026 14:53:49 +0000 (GMT) Received: from [9.39.24.89] (unknown [9.39.24.89]) by smtpav02.fra02v.mail.ibm.com (Postfix) with ESMTP; Wed, 29 Jul 2026 14:53:49 +0000 (GMT) Message-ID: Date: Wed, 29 Jul 2026 20:23:48 +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: 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-Proofpoint-Spam-Info: AW1haW4tMjYwNzI5MDEyMCBTYWx0ZWRfX7PwEIC5i/i1z tau3q7VkvAYih24i0EA6aDnpRlOb8/jI3SBTnuGxFjaGF2RS1ytT9kUahLrm1gY1hdoCoSkHLRr i3y3SBbYNX3BmkrGUVd4RXAWZIx6Vis= X-Proofpoint-GUID: lvEVG1Lzb5arMdrFsSqlaDWambzl81vs X-Proofpoint-ORIG-GUID: hSjyWncFqD0JwYfVNVkJ9lYIKGFQsoi5 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzI5MDEyMCBTYWx0ZWRfX2Q7akR7p1J/I qkycJu36rGa03FjXPgVbvsR3/sca8OnR/d8z1ZdiYdAxYr55McDKOOqTlVE1R9bQQgqDffPHB3x HbhzBNJFffHEFPP3q1yBgmQanClIQFeeAMwOzszQgQVS8b/PDwYFnuhnLKInTc+nU3qllYuot4k McdhvUGX3BZ7VC0RQMpSlAXu2ut1qKMw+e26JA2CCNqYaUX28OMYz9QVPc7aJ2ZuPv6G4zfh7cl 4ysuUE95xIOpgaJzqvwwc4u88BISCDIl/NmZjSO9AU6cyQpj/g6GXnr92wzkqEviuIvQGYKIrBZ K42GH9rKiNR/7kwXjPam8GQ+kkoJix0elv9y6GxBl0alVA0/43AXILL2TmLjNt54ViCe7oPSPsh HTriCSjTvvKuZ0QZCgA0i7twmkC6blKuS4oImaoWZM5ssrDzMoZZAYAIZCm1Shb//ZZzOs3PAtk 6e7x1injOh+eKH2uYkw== X-Authority-Analysis: v=2.4 cv=X5Vi7mTe c=1 sm=1 tr=0 ts=6a6a1407 cx=c_pps a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==: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=0DI864wKsEq8_xCAzw8A:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 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=2026-07-29_06,2026-07-28_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 impostorscore=0 lowpriorityscore=0 phishscore=0 priorityscore=1501 malwarescore=0 spamscore=0 suspectscore=0 bulkscore=0 adultscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607290120 On 7/21/26 10:01 AM, Shrikanth Hegde wrote: > > > 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? > Gentle Reminder. This might have fell through the cracks. Are there any concerns still to be addressed?