From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
To: paulmck@kernel.org
Cc: linux-kernel@vger.kernel.org,
David Woodhouse <dwmw2@infradead.org>,
Frederic Weisbecker <frederic@kernel.org>,
Neeraj Upadhyay <neeraj.upadhyay@kernel.org>,
Joel Fernandes <joelagnelf@nvidia.com>,
Josh Triplett <josh@joshtriplett.org>,
Boqun Feng <boqun@kernel.org>,
Uladzislau Rezki <urezki@gmail.com>,
Steven Rostedt <rostedt@goodmis.org>,
Lai Jiangshan <jiangshanlai@gmail.com>,
Zqiang <qiang.zhang@linux.dev>,
Davidlohr Bueso <dave@stgolabs.net>,
Kunwu Chan <kunwu.chan@gmail.com>,
Puranjay Mohan <puranjay@kernel.org>,
rcu@vger.kernel.org
Subject: Re: [PATCH v2 4/7] srcu: Add irqsave variants of the atomic SRCU readers
Date: Wed, 11 Nov 2026 15:13:34 -0500 [thread overview]
Message-ID: <9207ad1c-fe1c-4041-80c2-52723bc58486@efficios.com> (raw)
In-Reply-To: <31ba97d2-f02e-4c43-a9a6-5ed49263c511@paulmck-laptop>
On 2026-11-11 15:04, Paul E. McKenney wrote:
> Aside from this in the console output:
>
> rcu_torture_nmi_cleanup: nmi_readers set but no reader ever ran in NMI, so NMI readers went untested (no PMU, or NMIs unavailable here).
>
> Looking into it.
I expect this is a guest without a PMU. The NMI source is a perf
counter, and kvm.sh starts x86 guests without one. The readers in NMI
are then skipped, and this line says so. The nmi_calls test prints the
same kind of line.
I ran with:
--qemu-args "-cpu host,pmu=on"
With that, "NMI Reader Pipe:" and "NMI Reader Batch:" show up in the
statistics. The cover letter mentions it, but the changelog of patch 5
does not. I can add it there.
Thanks,
Mathieu
--
Mathieu Desnoyers
EfficiOS Inc.
https://www.efficios.com
next prev parent reply other threads:[~2026-11-11 20:13 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-11 14:59 [PATCH v2 0/7] srcu: NMI-safe atomic SRCU readers, and their irqsave forms Mathieu Desnoyers
2026-11-11 14:59 ` [PATCH v2 1/7] srcutiny: Do not call synchronize_rcu() from synchronize_srcu_atomic() Mathieu Desnoyers
2026-11-11 18:35 ` Paul E. McKenney
2026-11-11 14:59 ` [PATCH v2 2/7] srcu: Rule for using synchronize_srcu_atomic() from interrupt handlers Mathieu Desnoyers
2026-11-11 18:54 ` Paul E. McKenney
2026-11-11 14:59 ` [PATCH v2 3/7] srcu: Make atomic SRCU readers NMI-safe Mathieu Desnoyers
2026-11-11 19:55 ` Paul E. McKenney
2026-11-11 14:59 ` [PATCH v2 4/7] srcu: Add irqsave variants of the atomic SRCU readers Mathieu Desnoyers
2026-11-11 19:58 ` Paul E. McKenney
2026-11-11 20:04 ` Paul E. McKenney
2026-11-11 20:13 ` Mathieu Desnoyers [this message]
2026-11-11 14:59 ` [PATCH v2 5/7] rcutorture: Run NMI-safe SRCU readers from NMI Mathieu Desnoyers
2026-11-11 14:59 ` [PATCH v2 6/7] rcutorture: Test the irqsave forms of atomic SRCU readers Mathieu Desnoyers
2026-11-11 14:59 ` [PATCH v2 7/7] rcutorture: Check an atomic SRCU wait within an RCU reader Mathieu Desnoyers
2026-11-11 19:02 ` [PATCH v2 0/7] srcu: NMI-safe atomic SRCU readers, and their irqsave forms David Woodhouse
2026-11-11 19:33 ` Mathieu Desnoyers
2026-11-11 19:35 ` Paul E. McKenney
2026-11-11 19:37 ` David Woodhouse
2026-11-11 19:40 ` Mathieu Desnoyers
2026-11-11 19:50 ` Paul E. McKenney
2026-11-11 19:34 ` Paul E. McKenney
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