From: "Paul E. McKenney" <paulmck@kernel.org>
To: rcu@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: kernel-team@meta.com,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Boqun Feng <boqun@kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
lkmm@lists.linux.dev, Zqiang <qiang.zhang@linux.dev>,
Wang Lian <lianux.mm@gmail.com>,
Kunwu Chan <kunwu.chan@gmail.com>,
Bradley Morgan <brads@mainlining.org>,
"Paul E. McKenney" <paulmck@kernel.org>
Subject: [PATCH 06/28] hazptrtorture: Enable system-independent CPU overcommit
Date: Fri, 18 Sep 2026 17:00:34 -0700 [thread overview]
Message-ID: <20260919000056.3132131-6-paulmck@kernel.org> (raw)
In-Reply-To: <e9669b34-12c2-4cf2-a887-315f581f0789@paulmck-laptop>
This commit interprets negative values of the nreaders module parameter
as a number of readers per CPU, so that hazptrtorture.nreaders=-5 would
spawn five hazard-pointer reader kthreads per CPU. As CPUs go offline,
a number of readers determined by the overcommit are idled, so that
again when hazptrtorture.nreaders=-5, five readers would be idled for
each offline CPU.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Boqun Feng <boqun@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: <rcu@vger.kernel.org>
Cc: <lkmm@lists.linux.dev>
---
kernel/rcu/hazptrtorture.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/rcu/hazptrtorture.c b/kernel/rcu/hazptrtorture.c
index 9ecb86520551..e9ba25f156ac 100644
--- a/kernel/rcu/hazptrtorture.c
+++ b/kernel/rcu/hazptrtorture.c
@@ -362,7 +362,7 @@ static int hazptr_torture_reader(void *arg)
struct hazptr_torture *htp;
unsigned long lastsleep = jiffies;
long myid = (long)arg;
- int mynumonline = myid;
+ int mynumonline = myid % nr_cpu_ids;
int pipe_count;
DEFINE_TORTURE_RANDOM(rand);
@@ -622,7 +622,7 @@ static int __init hazptr_torture_init(void)
if (nreaders >= 0) {
nrealreaders = nreaders;
} else {
- nrealreaders = num_online_cpus() - 2 - nreaders;
+ nrealreaders = num_online_cpus() * -nreaders;
if (nrealreaders <= 0)
nrealreaders = 1;
}
--
2.40.1
next prev parent reply other threads:[~2026-09-19 0:01 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-18 23:59 [PATCH RFC v3 0/28] Simple hazard-pointer implementation and torture tests Paul E. McKenney
2026-09-19 0:00 ` [PATCH 01/28] hazptr: Implement Hazard Pointers Paul E. McKenney
2026-09-19 0:00 ` [PATCH 02/28] hazptr: Add refscale test Paul E. McKenney
2026-09-19 0:00 ` [PATCH 03/28] torture: Add a hazptrtorture.c torture test Paul E. McKenney
2026-09-19 0:00 ` [PATCH 04/28] hazptrtorture: Add testing of on-stack hazptr_ctx structures Paul E. McKenney
2026-09-19 0:00 ` [PATCH 05/28] hazptrtorture: Add microsecond-scale sleep in readers Paul E. McKenney
2026-09-19 0:00 ` Paul E. McKenney [this message]
2026-09-19 0:00 ` [PATCH 07/28] torture: Add a stutter_will_wait() function Paul E. McKenney
2026-09-19 0:00 ` [PATCH 08/28] hazptrtorture: Use mnemonic local variables for context information Paul E. McKenney
2026-09-19 0:00 ` [PATCH 09/28] hazptrtorture: Split hazptr_torture_reader_tail() from hazptr_torture_reader() Paul E. McKenney
2026-09-19 0:00 ` [PATCH 10/28] hazptrtorture: Add kthread to release deferred hazard pointers Paul E. McKenney
2026-09-19 0:00 ` [PATCH 11/28] hazptrtorture: Defer release of " Paul E. McKenney
2026-09-19 0:00 ` [PATCH 12/28] hazptrtorture: Add irq_acquire to acquire hazptr from irq Paul E. McKenney
2026-09-19 0:00 ` [PATCH 13/28] hazptrtorture: Use task_state_to_char() for task-state reporting Paul E. McKenney
2026-09-19 0:00 ` [PATCH 14/28] hazptrtorture: Pass hazptr_pending to hazptr_torture_reader_tail() Paul E. McKenney
2026-09-19 0:00 ` [PATCH 15/28] hazptrtorture: Add the ability to disable the writer kthread Paul E. McKenney
2026-09-19 0:00 ` [PATCH 16/28] hazptrtorture: Add irq_release to release hazptr from irq Paul E. McKenney
2026-09-19 0:00 ` [PATCH 17/28] hazptrtorture: Accumulate operation statistics Paul E. McKenney
2026-09-19 0:00 ` [PATCH 18/28] doc: Add hazptrtorture module parameters Paul E. McKenney
2026-09-19 0:00 ` [PATCH 19/28] hazptr: Permit detaching hazard pointers from contexts Paul E. McKenney
2026-09-19 0:00 ` [PATCH 20/28] hazptrtorture: Detach deferred and IPIed hazard pointers Paul E. McKenney
2026-09-19 0:00 ` [PATCH 21/28] hazptr: Introduce CONFIG_HAZPTR_DEBUG misuse detection Paul E. McKenney
2026-09-19 0:00 ` [PATCH 22/28] hazptrtorture: Fix hazptr ownership issue Paul E. McKenney
2026-09-19 0:00 ` [PATCH 23/28] hazptrtorture: Enable CONFIG_HAZPTR_DEBUG Paul E. McKenney
2026-09-19 0:00 ` [PATCH 24/28] hazptr: Upgrade kernel-doc headers Paul E. McKenney
2026-09-19 0:00 ` [PATCH 25/28] hazptrtorture: Fix inverted sleep condition in do_pending kthread Paul E. McKenney
2026-09-19 0:00 ` [PATCH 26/28] hazptr: Implement two-phase wildcard scan Paul E. McKenney
2026-09-19 0:00 ` [PATCH 27/28] hazptr: handle NULL address in hazptr_detach Paul E. McKenney
2026-09-19 0:00 ` [PATCH 28/28] torture.sh: Add hazptr torturing Paul E. McKenney
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