linux-kernel - Re: [PATCH v2 04/12] rcutorture: Make torture.sh --do-rt use CONFIG_PREEMPT

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20250402074211.tibxg1fJ@linutronix.de>
Date: Wed, 2 Apr 2025 09:42:11 +0200
From: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To: "Paul E. McKenney" <paulmck@...nel.org>
Cc: rcu@...r.kernel.org, Joel Fernandes <joelagnelf@...dia.com>,
	linux-kernel@...r.kernel.org, kernel-team@...a.com,
	rostedt@...dmis.org
Subject: Re: [PATCH v2 04/12] rcutorture: Make torture.sh --do-rt use
 CONFIG_PREEMPT_RT

On 2025-03-31 14:03:06 [-0700], Paul E. McKenney wrote:
> The torture.sh --do-rt command-line parameter is intended to mimic -rt
> kernels.  Now that CONFIG_PREEMPT_RT is upstream, this commit makes this
> mimicking more precise.
> 
> Note that testing of RCU priority boosting is disabled in favor
> of forward-progress testing of RCU callbacks.  If it turns out to be
> possible to make kernels built with CONFIG_PREEMPT_RT=y to tolerate
> testing of both, both will be enabled.

Not sure what you point at here: You can build a PREEMPT_RT kernel and
RCU boosting is enabled by default. You could disable it if needed.

Config wise you set CONFIG_PREEMPT_LAZY=n but in general
CONFIG_PREEMPT_LAZY=y should be used if possible. The preemption while
holding a sleeping spinlock is somehow bad for performance if a lot of
threads ask for it. But then it probably doesn't matter for testing.

You do set rcupdate.rcu_normal and rcupdate.rcu_expedited but RT has
rcu_normal_after_boot set by default. Not sure if this makes any
difference but I *think* that normal wins here.

> Signed-off-by: Paul E. McKenney <paulmck@...nel.org>
> Cc: Sebastian Andrzej Siewior <bigeasy@...utronix.de>

Sebastian