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From: Thomas Gleixner <tglx@linutronix.de>
To: Vishal Chourasia <vishalc@linux.ibm.com>,
	peterz@infradead.org, aboorvad@linux.ibm.com
Cc: boqun.feng@gmail.com, frederic@kernel.org, joelagnelf@nvidia.com,
	josh@joshtriplett.org, linux-kernel@vger.kernel.org,
	neeraj.upadhyay@kernel.org, paulmck@kernel.org,
	rcu@vger.kernel.org, rostedt@goodmis.org, srikar@linux.ibm.com,
	sshegde@linux.ibm.com, urezki@gmail.com, samir@linux.ibm.com,
	vishalc@linux.ibm.com
Subject: Re: [PATCH v3 2/2] cpuhp: Expedite RCU grace periods during SMT operations
Date: Wed, 25 Mar 2026 20:10:30 +0100	[thread overview]
Message-ID: <87fr5nendl.ffs@tglx> (raw)
In-Reply-To: <20260218083915.660252-6-vishalc@linux.ibm.com>

On Wed, Feb 18 2026 at 14:09, Vishal Chourasia wrote:
> Expedite synchronize_rcu during the SMT mode switch operation when
> initiated via /sys/devices/system/cpu/smt/control interface
>
> SMT mode switch operation i.e. between SMT 8 to SMT 1 or vice versa and
> others are user driven operations and therefore should complete as soon
> as possible. Switching SMT states involves iterating over a list of CPUs
> and performing hotplug operations. It was found these transitions took
> significantly large amount of time to complete particularly on
> high-core-count systems.

This changelog is neither explaining the underlying problem, nor
explaining why expedite solves it and does not contain numbers which
justify the change.

Thanks,

        tglx

      parent reply	other threads:[~2026-03-25 19:10 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-02-18  8:39 [PATCH v3 0/2] cpuhp: Improve SMT switch time via lock batching and RCU expedition Vishal Chourasia
2026-02-18  8:39 ` [PATCH v3 1/2] cpuhp: Optimize SMT switch operation by batching lock acquisition Vishal Chourasia
2026-03-25 19:09   ` Thomas Gleixner
2026-03-26 10:06     ` Vishal Chourasia
2026-02-18  8:39 ` [PATCH v3 2/2] cpuhp: Expedite RCU grace periods during SMT operations Vishal Chourasia
2026-02-27  1:13   ` Joel Fernandes
2026-03-02 11:47     ` Samir M
2026-03-06  5:44       ` Vishal Chourasia
2026-03-06 15:12         ` Paul E. McKenney
2026-03-20 18:49           ` Vishal Chourasia
2026-03-25 19:10   ` Thomas Gleixner [this message]

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