[PATCH 2/2] srcu-3: add SRCU operations to rcutorture

From: Paul E. McKenney
Date: Thu Jul 06 2006 - 14:34:48 EST

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Adds SRCU operations to rcutorture and updates rcutorture documentation.
Also increases the stress imposed by the rcutorture test.

Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
---

Documentation/RCU/torture.txt | 15 +++++
kernel/rcutorture.c | 121 ++++++++++++++++++++++++++++++++++++++++--
2 files changed, 132 insertions(+), 4 deletions(-)

diff -urpNa -X dontdiff linux-2.6.17-srcu/Documentation/RCU/torture.txt linux-2.6.17-torturesrcu/Documentation/RCU/torture.txt
--- linux-2.6.17-srcu/Documentation/RCU/torture.txt 2006-06-24 12:13:12.000000000 -0700
+++ linux-2.6.17-torturesrcu/Documentation/RCU/torture.txt 2006-06-26 18:50:33.000000000 -0700
@@ -118,6 +118,21 @@ o "Free-Block Circulation": Shows the nu
as it is only incremented if a torture structure's counter
somehow gets incremented farther than it should.

+Different implementations of RCU can provide implementation-specific
+additional information. For example, SRCU provides the following:
+
+ srcu-torture: rtc: f8cf46a8 ver: 355 tfle: 0 rta: 356 rtaf: 0 rtf: 346 rtmbe: 0
+ srcu-torture: Reader Pipe: 559738 939 0 0 0 0 0 0 0 0 0
+ srcu-torture: Reader Batch: 560434 243 0 0 0 0 0 0 0 0
+ srcu-torture: Free-Block Circulation: 355 354 353 352 351 350 349 348 347 346 0
+ srcu-torture: per-CPU(idx=1): 0(0,1) 1(0,1) 2(0,0) 3(0,1)
+
+The first four lines are similar to those for RCU. The last line shows
+the per-CPU counter state. The numbers in parentheses are the values
+of the "old" and "current" counters for the corresponding CPU. The
+"idx" value maps the "old" and "current" values to the underlying array,
+and is useful for debugging.
+

USAGE

diff -urpNa -X dontdiff linux-2.6.17-srcu/kernel/rcutorture.c linux-2.6.17-torturesrcu/kernel/rcutorture.c
--- linux-2.6.17-srcu/kernel/rcutorture.c 2006-06-30 15:03:35.000000000 -0700
+++ linux-2.6.17-torturesrcu/kernel/rcutorture.c 2006-07-02 07:34:35.000000000 -0700
@@ -44,6 +44,7 @@
#include <linux/delay.h>
#include <linux/byteorder/swabb.h>
#include <linux/stat.h>
+#include <linux/srcu.h>

MODULE_LICENSE("GPL");

@@ -53,7 +54,7 @@ static int stat_interval; /* Interval be
static int verbose; /* Print more debug info. */
static int test_no_idle_hz; /* Test RCU's support for tickless idle CPUs. */
static int shuffle_interval = 5; /* Interval between shuffles (in sec)*/
-static char *torture_type = "rcu"; /* What to torture. */
+static char *torture_type = "rcu"; /* What to torture: rcu, srcu. */

module_param(nreaders, int, 0);
MODULE_PARM_DESC(nreaders, "Number of RCU reader threads");
@@ -66,7 +67,7 @@ MODULE_PARM_DESC(test_no_idle_hz, "Test
module_param(shuffle_interval, int, 0);
MODULE_PARM_DESC(shuffle_interval, "Number of seconds between shuffles");
module_param(torture_type, charp, 0);
-MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh)");
+MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, srcu)");

#define TORTURE_FLAG "-torture:"
#define PRINTK_STRING(s) \
@@ -180,6 +181,7 @@ struct rcu_torture_ops {
void (*init)(void);
void (*cleanup)(void);
int (*readlock)(void);
+ void (*readdelay)(struct rcu_random_state *rrsp);
void (*readunlock)(int idx);
int (*completed)(void);
void (*deferredfree)(struct rcu_torture *p);
@@ -198,6 +200,18 @@ static int rcu_torture_read_lock(void)
return 0;
}

+static void rcu_read_delay(struct rcu_random_state *rrsp)
+{
+ long delay;
+ const long longdelay = 200;
+
+ /* We want there to be long-running readers, but not all the time. */
+
+ delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay);
+ if (!delay)
+ udelay(longdelay);
+}
+
static void rcu_torture_read_unlock(int idx)
{
rcu_read_unlock();
@@ -239,6 +253,7 @@ static struct rcu_torture_ops rcu_ops =
.init = NULL,
.cleanup = NULL,
.readlock = rcu_torture_read_lock,
+ .readdelay = rcu_read_delay,
.readunlock = rcu_torture_read_unlock,
.completed = rcu_torture_completed,
.deferredfree = rcu_torture_deferred_free,
@@ -275,6 +290,7 @@ static struct rcu_torture_ops rcu_bh_ops
.init = NULL,
.cleanup = NULL,
.readlock = rcu_bh_torture_read_lock,
+ .readdelay = rcu_read_delay, /* just reuse rcu's version. */
.readunlock = rcu_bh_torture_read_unlock,
.completed = rcu_bh_torture_completed,
.deferredfree = rcu_bh_torture_deferred_free,
@@ -282,8 +298,105 @@ static struct rcu_torture_ops rcu_bh_ops
.name = "rcu_bh"
};

+/*
+ * Definitions for srcu torture testing.
+ */
+
+static struct srcu_struct srcu_ctl;
+static struct list_head srcu_removed;
+
+static void srcu_torture_init(void)
+{
+ init_srcu_struct(&srcu_ctl);
+ INIT_LIST_HEAD(&srcu_removed);
+}
+
+static void srcu_torture_cleanup(void)
+{
+ synchronize_srcu(&srcu_ctl);
+ cleanup_srcu_struct(&srcu_ctl);
+}
+
+static int srcu_torture_read_lock(void)
+{
+ return srcu_read_lock(&srcu_ctl);
+}
+
+static void srcu_read_delay(struct rcu_random_state *rrsp)
+{
+ long delay;
+ const long uspertick = 1000000 / HZ;
+ const long longdelay = 10;
+
+ /* We want there to be long-running readers, but not all the time. */
+
+ delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay * uspertick);
+ if (!delay)
+ schedule_timeout_interruptible(longdelay);
+}
+
+static void srcu_torture_read_unlock(int idx)
+{
+ srcu_read_unlock(&srcu_ctl, idx);
+}
+
+static int srcu_torture_completed(void)
+{
+ return srcu_batches_completed(&srcu_ctl);
+}
+
+static void srcu_torture_deferred_free(struct rcu_torture *p)
+{
+ int i;
+ struct rcu_torture *rp;
+ struct rcu_torture *rp1;
+
+ synchronize_srcu(&srcu_ctl);
+ list_add(&p->rtort_free, &srcu_removed);
+ list_for_each_entry_safe(rp, rp1, &srcu_removed, rtort_free) {
+ i = rp->rtort_pipe_count;
+ if (i > RCU_TORTURE_PIPE_LEN)
+ i = RCU_TORTURE_PIPE_LEN;
+ atomic_inc(&rcu_torture_wcount[i]);
+ if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
+ rp->rtort_mbtest = 0;
+ list_del(&rp->rtort_free);
+ rcu_torture_free(rp);
+ }
+ }
+}
+
+int srcu_torture_stats(char *page)
+{
+ int cnt = 0;
+ int cpu;
+ int idx = srcu_ctl.completed & 0x1;
+
+ cnt += sprintf(&page[cnt], "%s%s per-CPU(idx=%d):",
+ torture_type, TORTURE_FLAG, idx);
+ for_each_possible_cpu(cpu) {
+ cnt += sprintf(&page[cnt], " %d(%d,%d)", cpu,
+ per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx],
+ per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx]);
+ }
+ cnt += sprintf(&page[cnt], "\n");
+ return cnt;
+}
+
+static struct rcu_torture_ops srcu_ops = {
+ .init = srcu_torture_init,
+ .cleanup = srcu_torture_cleanup,
+ .readlock = srcu_torture_read_lock,
+ .readdelay = srcu_read_delay,
+ .readunlock = srcu_torture_read_unlock,
+ .completed = srcu_torture_completed,
+ .deferredfree = srcu_torture_deferred_free,
+ .stats = srcu_torture_stats,
+ .name = "srcu"
+};
+
static struct rcu_torture_ops *torture_ops[] =
- { &rcu_ops, &rcu_bh_ops, NULL };
+ { &rcu_ops, &rcu_bh_ops, &srcu_ops, NULL };

/*
* RCU torture writer kthread. Repeatedly substitutes a new structure
@@ -359,7 +472,7 @@ rcu_torture_reader(void *arg)
}
if (p->rtort_mbtest == 0)
atomic_inc(&n_rcu_torture_mberror);
- udelay(rcu_random(&rand) & 0x7f);
+ cur_ops->readdelay(&rand);
preempt_disable();
pipe_count = p->rtort_pipe_count;
if (pipe_count > RCU_TORTURE_PIPE_LEN) {
-
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Next message: Dmitry Torokhov: "Re: lockdep input layer warnings."
Previous message: Paul E. McKenney: "[PATCH 0/2] srcu-3: add RCU variant that permits read-side blocking"
In reply to: Paul E. McKenney: "[PATCH 1/2] srcu-3: RCU variant permitting read-side blocking"
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