From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: linux-kernel@vger.kernel.org
Cc: mingo@elte.hu, laijs@cn.fujitsu.com, dipankar@in.ibm.com,
akpm@linux-foundation.org, mathieu.desnoyers@polymtl.ca,
josht@linux.vnet.ibm.com, dvhltc@us.ibm.com, niv@us.ibm.com,
tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org,
Josh Triplett <josh@joshtriplett.org>
Subject: [PATCH tip/core/rcu 1/3] rcutorture: Occasionally delay readers enough to make RCU force_quiescent_state
Date: Tue, 8 Sep 2009 15:54:35 -0700 [thread overview]
Message-ID: <12524504772607-git-send-email-> (raw)
In-Reply-To: <20090908225349.GA19524@linux.vnet.ibm.com>
From: Josh Triplett <josh@joshtriplett.org>
rcutorture already delays readers, but never for long enough to make RCU
force a quiescent state. Add an occasional delay of 50ms.
Signed-off-by: Josh Triplett <josh@joshtriplett.org>
---
kernel/rcutorture.c | 15 +++++++++------
1 files changed, 9 insertions(+), 6 deletions(-)
diff --git a/kernel/rcutorture.c b/kernel/rcutorture.c
index b33db53..328a825 100644
--- a/kernel/rcutorture.c
+++ b/kernel/rcutorture.c
@@ -281,14 +281,17 @@ static int rcu_torture_read_lock(void) __acquires(RCU)
static void rcu_read_delay(struct rcu_random_state *rrsp)
{
- long delay;
- const long longdelay = 200;
+ const unsigned long shortdelay_us = 200;
+ const unsigned long longdelay_ms = 50;
- /* We want there to be long-running readers, but not all the time. */
+ /* We want a short delay sometimes to make a reader delay the grace
+ * period, and we want a long delay occasionally to trigger
+ * force_quiescent_state. */
- delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay);
- if (!delay)
- udelay(longdelay);
+ if (!(rcu_random(rrsp) % (nrealreaders * 2000 * longdelay_ms)))
+ mdelay(longdelay_ms);
+ if (!(rcu_random(rrsp) % (nrealreaders * 2 * shortdelay_us)))
+ udelay(shortdelay_us);
}
static void rcu_torture_read_unlock(int idx) __releases(RCU)
--
1.5.2.5
next prev parent reply other threads:[~2009-09-08 22:54 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-09-08 22:53 [PATCH tip/core/rcu 0/3] increase rcutorture intensity and fix a couple resulting bugs Paul E. McKenney
2009-09-08 22:54 ` Paul E. McKenney [this message]
2009-09-12 7:45 ` [PATCH tip/core/rcu 1/3] rcutorture: Occasionally delay readers enough to make RCU force_quiescent_state Ingo Molnar
2009-09-12 14:36 ` Paul E. McKenney
2009-09-12 7:55 ` [tip:core/urgent] " tip-bot for Josh Triplett
2009-09-17 22:10 ` tip-bot for Josh Triplett
2009-09-08 22:54 ` [PATCH tip/core/rcu 2/3] Need to update rnp->gpnum if preemptable RCU is to be reliable Paul E. McKenney
2009-09-12 7:55 ` [tip:core/urgent] rcu: " tip-bot for Paul E. McKenney
2009-09-17 22:10 ` tip-bot for Paul E. McKenney
2009-09-08 22:54 ` [PATCH tip/core/rcu 3/3] Initialize multi-level RCU grace periods holding locks Paul E. McKenney
2009-09-12 7:55 ` [tip:core/urgent] rcu: " tip-bot for Paul E. McKenney
2009-09-17 22:10 ` tip-bot for Paul E. McKenney
2009-09-08 23:37 ` [PATCH tip/core/rcu 0/3] increase rcutorture intensity and fix a couple resulting bugs Steven Rostedt
2009-09-09 17:43 ` Valdis.Kletnieks
2009-09-09 18:23 ` Paul E. McKenney
2009-09-12 7:46 ` Ingo Molnar
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