// SPDX-License-Identifier: GPL-2.0+
//
// Scalability test comparing RCU vs other mechanisms
// for acquiring references on objects.
//
// Copyright (C) Google, 2020.
//
// Author: Joel Fernandes <[email protected]>
#define pr_fmt(fmt) fmt
#include <linux/atomic.h>
#include <linux/bitops.h>
#include <linux/completion.h>
#include <linux/cpu.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/kthread.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/notifier.h>
#include <linux/percpu.h>
#include <linux/rcupdate.h>
#include <linux/rcupdate_trace.h>
#include <linux/reboot.h>
#include <linux/sched.h>
#include <linux/seq_buf.h>
#include <linux/spinlock.h>
#include <linux/smp.h>
#include <linux/stat.h>
#include <linux/srcu.h>
#include <linux/slab.h>
#include <linux/torture.h>
#include <linux/types.h>
#include "rcu.h"
#define SCALE_FLAG "-ref-scale: "
#define SCALEOUT(s, x...) \
pr_alert("%s" SCALE_FLAG s, scale_type, ## x)
#define VERBOSE_SCALEOUT(s, x...) \
do { \
if (verbose) \
pr_alert("%s" SCALE_FLAG s "\n", scale_type, ## x); \
} while (0)
static atomic_t verbose_batch_ctr;
#define VERBOSE_SCALEOUT_BATCH(s, x...) \
do { \
if (verbose && \
(verbose_batched <= 0 || \
!(atomic_inc_return(&verbose_batch_ctr) % verbose_batched))) { \
schedule_timeout_uninterruptible(1); \
pr_alert("%s" SCALE_FLAG s "\n", scale_type, ## x); \
} \
} while (0)
#define SCALEOUT_ERRSTRING(s, x...) pr_alert("%s" SCALE_FLAG "!!! " s "\n", scale_type, ## x)
MODULE_DESCRIPTION("Scalability test for object reference mechanisms");
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Joel Fernandes (Google) <[email protected]>");
static char *scale_type = "rcu";
module_param(scale_type, charp, 0444);
MODULE_PARM_DESC(scale_type, "Type of test (rcu, srcu, refcnt, rwsem, rwlock.");
torture_param(int, verbose, 0, "Enable verbose debugging printk()s");
torture_param(int, verbose_batched, 0, "Batch verbose debugging printk()s");
// Wait until there are multiple CPUs before starting test.
torture_param(int, holdoff, IS_BUILTIN(CONFIG_RCU_REF_SCALE_TEST) ? 10 : 0,
"Holdoff time before test start (s)");
// Number of typesafe_lookup structures, that is, the degree of concurrency.
torture_param(long, lookup_instances, 0, "Number of typesafe_lookup structures.");
// Number of loops per experiment, all readers execute operations concurrently.
torture_param(long, loops, 10000, "Number of loops per experiment.");
// Number of readers, with -1 defaulting to about 75% of the CPUs.
torture_param(int, nreaders, -1, "Number of readers, -1 for 75% of CPUs.");
// Number of runs.
torture_param(int, nruns, 30, "Number of experiments to run.");
// Reader delay in nanoseconds, 0 for no delay.
torture_param(int, readdelay, 0, "Read-side delay in nanoseconds.");
#ifdef MODULE
# define REFSCALE_SHUTDOWN 0
#else
# define REFSCALE_SHUTDOWN 1
#endif
torture_param(bool, shutdown, REFSCALE_SHUTDOWN,
"Shutdown at end of scalability tests.");
struct reader_task {
struct task_struct *task;
int start_reader;
wait_queue_head_t wq;
u64 last_duration_ns;
};
static struct task_struct *shutdown_task;
static wait_queue_head_t shutdown_wq;
static struct task_struct *main_task;
static wait_queue_head_t main_wq;
static int shutdown_start;
static struct reader_task *reader_tasks;
// Number of readers that are part of the current experiment.
static atomic_t nreaders_exp;
// Use to wait for all threads to start.
static atomic_t n_init;
static atomic_t n_started;
static atomic_t n_warmedup;
static atomic_t n_cooleddown;
// Track which experiment is currently running.
static int exp_idx;
// Operations vector for selecting different types of tests.
struct ref_scale_ops {
bool (*init)(void);
void (*cleanup)(void);
void (*readsection)(const int nloops);
void (*delaysection)(const int nloops, const int udl, const int ndl);
const char *name;
};
static const struct ref_scale_ops *cur_ops;
static void un_delay(const int udl, const int ndl)
{
if (udl)
udelay(udl);
if (ndl)
ndelay(ndl);
}
static void ref_rcu_read_section(const int nloops)
{
int i;
for (i = nloops; i >= 0; i--) {
rcu_read_lock();
rcu_read_unlock();
}
}
static void ref_rcu_delay_section(const int nloops, const int udl, const int ndl)
{
int i;
for (i = nloops; i >= 0; i--) {
rcu_read_lock();
un_delay(udl, ndl);
rcu_read_unlock();
}
}
static bool rcu_sync_scale_init(void)
{
return true;
}
static const struct ref_scale_ops rcu_ops = {
.init = rcu_sync_scale_init,
.readsection = ref_rcu_read_section,
.delaysection = ref_rcu_delay_section,
.name = "rcu"
};
// Definitions for SRCU ref scale testing.
DEFINE_STATIC_SRCU(srcu_refctl_scale);
static struct srcu_struct *srcu_ctlp = &srcu_refctl_scale;
static void srcu_ref_scale_read_section(const int nloops)
{
int i;
int idx;
for (i = nloops; i >= 0; i--) {
idx = srcu_read_lock(srcu_ctlp);
srcu_read_unlock(srcu_ctlp, idx);
}
}
static void srcu_ref_scale_delay_section(const int nloops, const int udl, const int ndl)
{
int i;
int idx;
for (i = nloops; i >= 0; i--) {
idx = srcu_read_lock(srcu_ctlp);
un_delay(udl, ndl);
srcu_read_unlock(srcu_ctlp, idx);
}
}
static const struct ref_scale_ops srcu_ops = {
.init = rcu_sync_scale_init,
.readsection = srcu_ref_scale_read_section,
.delaysection = srcu_ref_scale_delay_section,
.name = "srcu"
};
#ifdef CONFIG_TASKS_RCU
// Definitions for RCU Tasks ref scale testing: Empty read markers.
// These definitions also work for RCU Rude readers.
static void rcu_tasks_ref_scale_read_section(const int nloops)
{
int i;
for (i = nloops; i >= 0; i--)
continue;
}
static void rcu_tasks_ref_scale_delay_section(const int nloops, const int udl, const int ndl)
{
int i;
for (i = nloops; i >= 0; i--)
un_delay(udl, ndl);
}
static const struct ref_scale_ops rcu_tasks_ops = {
.init = rcu_sync_scale_init,
.readsection = rcu_tasks_ref_scale_read_section,
.delaysection = rcu_tasks_ref_scale_delay_section,
.name = "rcu-tasks"
};
#define RCU_TASKS_OPS &rcu_tasks_ops,
#else // #ifdef CONFIG_TASKS_RCU
#define RCU_TASKS_OPS
#endif // #else // #ifdef CONFIG_TASKS_RCU
#ifdef CONFIG_TASKS_TRACE_RCU
// Definitions for RCU Tasks Trace ref scale testing.
static void rcu_trace_ref_scale_read_section(const int nloops)
{
int i;
for (i = nloops; i >= 0; i--) {
rcu_read_lock_trace();
rcu_read_unlock_trace();
}
}
static void rcu_trace_ref_scale_delay_section(const int nloops, const int udl, const int ndl)
{
int i;
for (i = nloops; i >= 0; i--) {
rcu_read_lock_trace();
un_delay(udl, ndl);
rcu_read_unlock_trace();
}
}
static const struct ref_scale_ops rcu_trace_ops = {
.init = rcu_sync_scale_init,
.readsection = rcu_trace_ref_scale_read_section,
.delaysection = rcu_trace_ref_scale_delay_section,
.name = "rcu-trace"
};
#define RCU_TRACE_OPS &rcu_trace_ops,
#else // #ifdef CONFIG_TASKS_TRACE_RCU
#define RCU_TRACE_OPS
#endif // #else // #ifdef CONFIG_TASKS_TRACE_RCU
// Definitions for reference count
static atomic_t refcnt;
static void ref_refcnt_section(const int nloops)
{
int i;
for (i = nloops; i >= 0; i--) {
atomic_inc(&refcnt);
atomic_dec(&refcnt);
}
}
static void ref_refcnt_delay_section(const int nloops, const int udl, const int ndl)
{
int i;
for (i = nloops; i >= 0; i--) {
atomic_inc(&refcnt);
un_delay(udl, ndl);
atomic_dec(&refcnt);
}
}
static const struct ref_scale_ops refcnt_ops = {
.init = rcu_sync_scale_init,
.readsection = ref_refcnt_section,
.delaysection = ref_refcnt_delay_section,
.name = "refcnt"
};
// Definitions for rwlock
static rwlock_t test_rwlock;
static bool ref_rwlock_init(void)
{
rwlock_init(&test_rwlock);
return true;
}
static void ref_rwlock_section(const int nloops)
{
int i;
for (i = nloops; i >= 0; i--) {
read_lock(&test_rwlock);
read_unlock(&test_rwlock);
}
}
static void ref_rwlock_delay_section(const int nloops, const int udl, const int ndl)
{
int i;
for (i = nloops; i >= 0; i--) {
read_lock(&test_rwlock);
un_delay(udl, ndl);
read_unlock(&test_rwlock);
}
}
static const struct ref_scale_ops rwlock_ops = {
.init = ref_rwlock_init,
.readsection = ref_rwlock_section,
.delaysection = ref_rwlock_delay_section,
.name = "rwlock"
};
// Definitions for rwsem
static struct rw_semaphore test_rwsem;
static bool ref_rwsem_init(void)
{
init_rwsem(&test_rwsem);
return true;
}
static void ref_rwsem_section(const int nloops)
{
int i;
for (i = nloops; i >= 0; i--) {
down_read(&test_rwsem);
up_read(&test_rwsem);
}
}
static void ref_rwsem_delay_section(const int nloops, const int udl, const int ndl)
{
int i;
for (i = nloops; i >= 0; i--) {
down_read(&test_rwsem);
un_delay(udl, ndl);
up_read(&test_rwsem);
}
}
static const struct ref_scale_ops rwsem_ops = {
.init = ref_rwsem_init,
.readsection = ref_rwsem_section,
.delaysection = ref_rwsem_delay_section,
.name = "rwsem"
};
// Definitions for global spinlock
static DEFINE_RAW_SPINLOCK(test_lock);
static void ref_lock_section(const int nloops)
{
int i;
preempt_disable();
for (i = nloops; i >= 0; i--) {
raw_spin_lock(&test_lock);
raw_spin_unlock(&test_lock);
}
preempt_enable();
}
static void ref_lock_delay_section(const int nloops, const int udl, const int ndl)
{
int i;
preempt_disable();
for (i = nloops; i >= 0; i--) {
raw_spin_lock(&test_lock);
un_delay(udl, ndl);
raw_spin_unlock(&test_lock);
}
preempt_enable();
}
static const struct ref_scale_ops lock_ops = {
.readsection = ref_lock_section,
.delaysection = ref_lock_delay_section,
.name = "lock"
};
// Definitions for global irq-save spinlock
static void ref_lock_irq_section(const int nloops)
{
unsigned long flags;
int i;
preempt_disable();
for (i = nloops; i >= 0; i--) {
raw_spin_lock_irqsave(&test_lock, flags);
raw_spin_unlock_irqrestore(&test_lock, flags);
}
preempt_enable();
}
static void ref_lock_irq_delay_section(const int nloops, const int udl, const int ndl)
{
unsigned long flags;
int i;
preempt_disable();
for (i = nloops; i >= 0; i--) {
raw_spin_lock_irqsave(&test_lock, flags);
un_delay(udl, ndl);
raw_spin_unlock_irqrestore(&test_lock, flags);
}
preempt_enable();
}
static const struct ref_scale_ops lock_irq_ops = {
.readsection = ref_lock_irq_section,
.delaysection = ref_lock_irq_delay_section,
.name = "lock-irq"
};
// Definitions acquire-release.
static DEFINE_PER_CPU(unsigned long, test_acqrel);
static void ref_acqrel_section(const int nloops)
{
unsigned long x;
int i;
preempt_disable();
for (i = nloops; i >= 0; i--) {
x = smp_load_acquire(this_cpu_ptr(&test_acqrel));
smp_store_release(this_cpu_ptr(&test_acqrel), x + 1);
}
preempt_enable();
}
static void ref_acqrel_delay_section(const int nloops, const int udl, const int ndl)
{
unsigned long x;
int i;
preempt_disable();
for (i = nloops; i >= 0; i--) {
x = smp_load_acquire(this_cpu_ptr(&test_acqrel));
un_delay(udl, ndl);
smp_store_release(this_cpu_ptr(&test_acqrel), x + 1);
}
preempt_enable();
}
static const struct ref_scale_ops acqrel_ops = {
.readsection = ref_acqrel_section,
.delaysection = ref_acqrel_delay_section,
.name = "acqrel"
};
static volatile u64 stopopts;
static void ref_clock_section(const int nloops)
{
u64 x = 0;
int i;
preempt_disable();
for (i = nloops; i >= 0; i--)
x += ktime_get_real_fast_ns();
preempt_enable();
stopopts = x;
}
static void ref_clock_delay_section(const int nloops, const int udl, const int ndl)
{
u64 x = 0;
int i;
preempt_disable();
for (i = nloops; i >= 0; i--) {
x += ktime_get_real_fast_ns();
un_delay(udl, ndl);
}
preempt_enable();
stopopts = x;
}
static const struct ref_scale_ops clock_ops = {
.readsection = ref_clock_section,
.delaysection = ref_clock_delay_section,
.name = "clock"
};
static void ref_jiffies_section(const int nloops)
{
u64 x = 0;
int i;
preempt_disable();
for (i = nloops; i >= 0; i--)
x += jiffies;
preempt_enable();
stopopts = x;
}
static void ref_jiffies_delay_section(const int nloops, const int udl, const int ndl)
{
u64 x = 0;
int i;
preempt_disable();
for (i = nloops; i >= 0; i--) {
x += jiffies;
un_delay(udl, ndl);
}
preempt_enable();
stopopts = x;
}
static const struct ref_scale_ops jiffies_ops = {
.readsection = ref_jiffies_section,
.delaysection = ref_jiffies_delay_section,
.name = "jiffies"
};
////////////////////////////////////////////////////////////////////////
//
// Methods leveraging SLAB_TYPESAFE_BY_RCU.
//
// Item to look up in a typesafe manner. Array of pointers to these.
struct refscale_typesafe {
atomic_t rts_refctr; // Used by all flavors
spinlock_t rts_lock;
seqlock_t rts_seqlock;
unsigned int a;
unsigned int b;
};
static struct kmem_cache *typesafe_kmem_cachep;
static struct refscale_typesafe **rtsarray;
static long rtsarray_size;
static DEFINE_TORTURE_RANDOM_PERCPU(refscale_rand);
static bool (*rts_acquire)(struct refscale_typesafe *rtsp, unsigned int *start);
static bool (*rts_release)(struct refscale_typesafe *rtsp, unsigned int start);
// Conditionally acquire an explicit in-structure reference count.
static bool typesafe_ref_acquire(struct refscale_typesafe *rtsp, unsigned int *start)
{
return atomic_inc_not_zero(&rtsp->rts_refctr);
}
// Unconditionally release an explicit in-structure reference count.
static bool typesafe_ref_release(struct refscale_typesafe *rtsp, unsigned int start)
{
if (!atomic_dec_return(&rtsp->rts_refctr)) {
WRITE_ONCE(rtsp->a, rtsp->a + 1);
kmem_cache_free(typesafe_kmem_cachep, rtsp);
}
return true;
}
// Unconditionally acquire an explicit in-structure spinlock.
static bool typesafe_lock_acquire(struct refscale_typesafe *rtsp, unsigned int *start)
{
spin_lock(&rtsp->rts_lock);
return true;
}
// Unconditionally release an explicit in-structure spinlock.
static bool typesafe_lock_release(struct refscale_typesafe *rtsp, unsigned int start)
{
spin_unlock(&rtsp->rts_lock);
return true;
}
// Unconditionally acquire an explicit in-structure sequence lock.
static bool typesafe_seqlock_acquire(struct refscale_typesafe *rtsp, unsigned int *start)
{
*start = read_seqbegin(&rtsp->rts_seqlock);
return true;
}
// Conditionally release an explicit in-structure sequence lock. Return
// true if this release was successful, that is, if no retry is required.
static bool typesafe_seqlock_release(struct refscale_typesafe *rtsp, unsigned int start)
{
return !read_seqretry(&rtsp->rts_seqlock, start);
}
// Do a read-side critical section with the specified delay in
// microseconds and nanoseconds inserted so as to increase probability
// of failure.
static void typesafe_delay_section(const int nloops, const int udl, const int ndl)
{
unsigned int a;
unsigned int b;
int i;
long idx;
struct refscale_typesafe *rtsp;
unsigned int start;
for (i = nloops; i >= 0; i--) {
preempt_disable();
idx = torture_random(this_cpu_ptr(&refscale_rand)) % rtsarray_size;
preempt_enable();
retry:
rcu_read_lock();
rtsp = rcu_dereference(rtsarray[idx]);
a = READ_ONCE(rtsp->a);
if (!rts_acquire(rtsp, &start)) {
rcu_read_unlock();
goto retry;
}
if (a != READ_ONCE(rtsp->a)) {
(void)rts_release(rtsp, start);
rcu_read_unlock();
goto retry;
}
un_delay(udl, ndl);
b = READ_ONCE(rtsp->a);
// Remember, seqlock read-side release can fail.
if (!rts_release(rtsp, start)) {
rcu_read_unlock();
goto retry;
}
WARN_ONCE(a != b, "Re-read of ->a changed from %u to %u.\n", a, b);
b = rtsp->b;
rcu_read_unlock();
WARN_ON_ONCE(a * a != b);
}
}
// Because the acquisition and release methods are expensive, there
// is no point in optimizing away the un_delay() function's two checks.
// Thus simply define typesafe_read_section() as a simple wrapper around
// typesafe_delay_section().
static void typesafe_read_section(const int nloops)
{
typesafe_delay_section(nloops, 0, 0);
}
// Allocate and initialize one refscale_typesafe structure.
static struct refscale_typesafe *typesafe_alloc_one(void)
{
struct refscale_typesafe *rtsp;
rtsp = kmem_cache_alloc(typesafe_kmem_cachep, GFP_KERNEL);
if (!rtsp)
return NULL;
atomic_set(&rtsp->rts_refctr, 1);
WRITE_ONCE(rtsp->a, rtsp->a + 1);
WRITE_ONCE(rtsp->b, rtsp->a * rtsp->a);
return rtsp;
}
// Slab-allocator constructor for refscale_typesafe structures created
// out of a new slab of system memory.
static void refscale_typesafe_ctor(void *rtsp_in)
{
struct refscale_typesafe *rtsp = rtsp_in;
spin_lock_init(&rtsp->rts_lock);
seqlock_init(&rtsp->rts_seqlock);
preempt_disable();
rtsp->a = torture_random(this_cpu_ptr(&refscale_rand));
preempt_enable();
}
static const struct ref_scale_ops typesafe_ref_ops;
static const struct ref_scale_ops typesafe_lock_ops;
static const struct ref_scale_ops typesafe_seqlock_ops;
// Initialize for a typesafe test.
static bool typesafe_init(void)
{
long idx;
long si = lookup_instances;
typesafe_kmem_cachep = kmem_cache_create("refscale_typesafe",
sizeof(struct refscale_typesafe), sizeof(void *),
SLAB_TYPESAFE_BY_RCU, refscale_typesafe_ctor);
if (!typesafe_kmem_cachep)
return false;
if (si < 0)
si = -si * nr_cpu_ids;
else if (si == 0)
si = nr_cpu_ids;
rtsarray_size = si;
rtsarray = kcalloc(si, sizeof(*rtsarray), GFP_KERNEL);
if (!rtsarray)
return false;
for (idx = 0; idx < rtsarray_size; idx++) {
rtsarray[idx] = typesafe_alloc_one();
if (!rtsarray[idx])
return false;
}
if (cur_ops == &typesafe_ref_ops) {
rts_acquire = typesafe_ref_acquire;
rts_release = typesafe_ref_release;
} else if (cur_ops == &typesafe_lock_ops) {
rts_acquire = typesafe_lock_acquire;
rts_release = typesafe_lock_release;
} else if (cur_ops == &typesafe_seqlock_ops) {
rts_acquire = typesafe_seqlock_acquire;
rts_release = typesafe_seqlock_release;
} else {
WARN_ON_ONCE(1);
return false;
}
return true;
}
// Clean up after a typesafe test.
static void typesafe_cleanup(void)
{
long idx;
if (rtsarray) {
for (idx = 0; idx < rtsarray_size; idx++)
kmem_cache_free(typesafe_kmem_cachep, rtsarray[idx]);
kfree(rtsarray);
rtsarray = NULL;
rtsarray_size = 0;
}
kmem_cache_destroy(typesafe_kmem_cachep);
typesafe_kmem_cachep = NULL;
rts_acquire = NULL;
rts_release = NULL;
}
// The typesafe_init() function distinguishes these structures by address.
static const struct ref_scale_ops typesafe_ref_ops = {
.init = typesafe_init,
.cleanup = typesafe_cleanup,
.readsection = typesafe_read_section,
.delaysection = typesafe_delay_section,
.name = "typesafe_ref"
};
static const struct ref_scale_ops typesafe_lock_ops = {
.init = typesafe_init,
.cleanup = typesafe_cleanup,
.readsection = typesafe_read_section,
.delaysection = typesafe_delay_section,
.name = "typesafe_lock"
};
static const struct ref_scale_ops typesafe_seqlock_ops = {
.init = typesafe_init,
.cleanup = typesafe_cleanup,
.readsection = typesafe_read_section,
.delaysection = typesafe_delay_section,
.name = "typesafe_seqlock"
};
static void rcu_scale_one_reader(void)
{
if (readdelay <= 0)
cur_ops->readsection(loops);
else
cur_ops->delaysection(loops, readdelay / 1000, readdelay % 1000);
}
// Reader kthread. Repeatedly does empty RCU read-side
// critical section, minimizing update-side interference.
static int
ref_scale_reader(void *arg)
{
unsigned long flags;
long me = (long)arg;
struct reader_task *rt = &(reader_tasks[me]);
u64 start;
s64 duration;
VERBOSE_SCALEOUT_BATCH("ref_scale_reader %ld: task started", me);
WARN_ON_ONCE(set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids)));
set_user_nice(current, MAX_NICE);
atomic_inc(&n_init);
if (holdoff)
schedule_timeout_interruptible(holdoff * HZ);
repeat:
VERBOSE_SCALEOUT_BATCH("ref_scale_reader %ld: waiting to start next experiment on cpu %d", me, raw_smp_processor_id());
// Wait for signal that this reader can start.
wait_event(rt->wq, (atomic_read(&nreaders_exp) && smp_load_acquire(&rt->start_reader)) ||
torture_must_stop());
if (torture_must_stop())
goto end;
// Make sure that the CPU is affinitized appropriately during testing.
WARN_ON_ONCE(raw_smp_processor_id() != me);
WRITE_ONCE(rt->start_reader, 0);
if (!atomic_dec_return(&n_started))
while (atomic_read_acquire(&n_started))
cpu_relax();
VERBOSE_SCALEOUT_BATCH("ref_scale_reader %ld: experiment %d started", me, exp_idx);
// To reduce noise, do an initial cache-warming invocation, check
// in, and then keep warming until everyone has checked in.
rcu_scale_one_reader();
if (!atomic_dec_return(&n_warmedup))
while (atomic_read_acquire(&n_warmedup))
rcu_scale_one_reader();
// Also keep interrupts disabled. This also has the effect
// of preventing entries into slow path for rcu_read_unlock().
local_irq_save(flags);
start = ktime_get_mono_fast_ns();
rcu_scale_one_reader();
duration = ktime_get_mono_fast_ns() - start;
local_irq_restore(flags);
rt->last_duration_ns = WARN_ON_ONCE(duration < 0) ? 0 : duration;
// To reduce runtime-skew noise, do maintain-load invocations until
// everyone is done.
if (!atomic_dec_return(&n_cooleddown))
while (atomic_read_acquire(&n_cooleddown))
rcu_scale_one_reader();
if (atomic_dec_and_test(&nreaders_exp))
wake_up(&main_wq);
VERBOSE_SCALEOUT_BATCH("ref_scale_reader %ld: experiment %d ended, (readers remaining=%d)",
me, exp_idx, atomic_read(&nreaders_exp));
if (!torture_must_stop())
goto repeat;
end:
torture_kthread_stopping("ref_scale_reader");
return 0;
}
static void reset_readers(void)
{
int i;
struct reader_task *rt;
for (i = 0; i < nreaders; i++) {
rt = &(reader_tasks[i]);
rt->last_duration_ns = 0;
}
}
// Print the results of each reader and return the sum of all their durations.
static u64 process_durations(int n)
{
int i;
struct reader_task *rt;
struct seq_buf s;
char *buf;
u64 sum = 0;
buf = kmalloc(800 + 64, GFP_KERNEL);
if (!buf)
return 0;
seq_buf_init(&s, buf, 800 + 64);
seq_buf_printf(&s, "Experiment #%d (Format: <THREAD-NUM>:<Total loop time in ns>)",
exp_idx);
for (i = 0; i < n && !torture_must_stop(); i++) {
rt = &(reader_tasks[i]);
if (i % 5 == 0)
seq_buf_putc(&s, '\n');
if (seq_buf_used(&s) >= 800) {
pr_alert("%s", seq_buf_str(&s));
seq_buf_clear(&s);
}
seq_buf_printf(&s, "%d: %llu\t", i, rt->last_duration_ns);
sum += rt->last_duration_ns;
}
pr_alert("%s\n", seq_buf_str(&s));
kfree(buf);
return sum;
}
// The main_func is the main orchestrator, it performs a bunch of
// experiments. For every experiment, it orders all the readers
// involved to start and waits for them to finish the experiment. It
// then reads their timestamps and starts the next experiment. Each
// experiment progresses from 1 concurrent reader to N of them at which
// point all the timestamps are printed.
static int main_func(void *arg)
{
int exp, r;
char buf1[64];
char *buf;
u64 *result_avg;
set_cpus_allowed_ptr(current, cpumask_of(nreaders % nr_cpu_ids));
set_user_nice(current, MAX_NICE);
VERBOSE_SCALEOUT("main_func task started");
result_avg = kzalloc(nruns * sizeof(*result_avg), GFP_KERNEL);
buf = kzalloc(800 + 64, GFP_KERNEL);
if (!result_avg || !buf) {
SCALEOUT_ERRSTRING("out of memory");
goto oom_exit;
}
if (holdoff)
schedule_timeout_interruptible(holdoff * HZ);
// Wait for all threads to start.
atomic_inc(&n_init);
while (atomic_read(&n_init) < nreaders + 1)
schedule_timeout_uninterruptible(1);
// Start exp readers up per experiment
for (exp = 0; exp < nruns && !torture_must_stop(); exp++) {
if (torture_must_stop())
goto end;
reset_readers();
atomic_set(&nreaders_exp, nreaders);
atomic_set(&n_started, nreaders);
atomic_set(&n_warmedup, nreaders);
atomic_set(&n_cooleddown, nreaders);
exp_idx = exp;
for (r = 0; r < nreaders; r++) {
smp_store_release(&reader_tasks[r].start_reader, 1);
wake_up(&reader_tasks[r].wq);
}
VERBOSE_SCALEOUT("main_func: experiment started, waiting for %d readers",
nreaders);
wait_event(main_wq,
!atomic_read(&nreaders_exp) || torture_must_stop());
VERBOSE_SCALEOUT("main_func: experiment ended");
if (torture_must_stop())
goto end;
result_avg[exp] = div_u64(1000 * process_durations(nreaders), nreaders * loops);
}
// Print the average of all experiments
SCALEOUT("END OF TEST. Calculating average duration per loop (nanoseconds)...\n");
pr_alert("Runs\tTime(ns)\n");
for (exp = 0; exp < nruns; exp++) {
u64 avg;
u32 rem;
avg = div_u64_rem(result_avg[exp], 1000, &rem);
sprintf(buf1, "%d\t%llu.%03u\n", exp + 1, avg, rem);
strcat(buf, buf1);
if (strlen(buf) >= 800) {
pr_alert("%s", buf);
buf[0] = 0;
}
}
pr_alert("%s", buf);
oom_exit:
// This will shutdown everything including us.
if (shutdown) {
shutdown_start = 1;
wake_up(&shutdown_wq);
}
// Wait for torture to stop us
while (!torture_must_stop())
schedule_timeout_uninterruptible(1);
end:
torture_kthread_stopping("main_func");
kfree(result_avg);
kfree(buf);
return 0;
}
static void
ref_scale_print_module_parms(const struct ref_scale_ops *cur_ops, const char *tag)
{
pr_alert("%s" SCALE_FLAG
"--- %s: verbose=%d verbose_batched=%d shutdown=%d holdoff=%d lookup_instances=%ld loops=%ld nreaders=%d nruns=%d readdelay=%d\n", scale_type, tag,
verbose, verbose_batched, shutdown, holdoff, lookup_instances, loops, nreaders, nruns, readdelay);
}
static void
ref_scale_cleanup(void)
{
int i;
if (torture_cleanup_begin())
return;
if (!cur_ops) {
torture_cleanup_end();
return;
}
if (reader_tasks) {
for (i = 0; i < nreaders; i++)
torture_stop_kthread("ref_scale_reader",
reader_tasks[i].task);
}
kfree(reader_tasks);
torture_stop_kthread("main_task", main_task);
kfree(main_task);
// Do scale-type-specific cleanup operations.
if (cur_ops->cleanup != NULL)
cur_ops->cleanup();
torture_cleanup_end();
}
// Shutdown kthread. Just waits to be awakened, then shuts down system.
static int
ref_scale_shutdown(void *arg)
{
wait_event_idle(shutdown_wq, shutdown_start);
smp_mb(); // Wake before output.
ref_scale_cleanup();
kernel_power_off();
return -EINVAL;
}
static int __init
ref_scale_init(void)
{
long i;
int firsterr = 0;
static const struct ref_scale_ops *scale_ops[] = {
&rcu_ops, &srcu_ops, RCU_TRACE_OPS RCU_TASKS_OPS &refcnt_ops, &rwlock_ops,
&rwsem_ops, &lock_ops, &lock_irq_ops, &acqrel_ops, &clock_ops, &jiffies_ops,
&typesafe_ref_ops, &typesafe_lock_ops, &typesafe_seqlock_ops,
};
if (!torture_init_begin(scale_type, verbose))
return -EBUSY;
for (i = 0; i < ARRAY_SIZE(scale_ops); i++) {
cur_ops = scale_ops[i];
if (strcmp(scale_type, cur_ops->name) == 0)
break;
}
if (i == ARRAY_SIZE(scale_ops)) {
pr_alert("rcu-scale: invalid scale type: \"%s\"\n", scale_type);
pr_alert("rcu-scale types:");
for (i = 0; i < ARRAY_SIZE(scale_ops); i++)
pr_cont(" %s", scale_ops[i]->name);
pr_cont("\n");
firsterr = -EINVAL;
cur_ops = NULL;
goto unwind;
}
if (cur_ops->init)
if (!cur_ops->init()) {
firsterr = -EUCLEAN;
goto unwind;
}
ref_scale_print_module_parms(cur_ops, "Start of test");
// Shutdown task
if (shutdown) {
init_waitqueue_head(&shutdown_wq);
firsterr = torture_create_kthread(ref_scale_shutdown, NULL,
shutdown_task);
if (torture_init_error(firsterr))
goto unwind;
schedule_timeout_uninterruptible(1);
}
// Reader tasks (default to ~75% of online CPUs).
if (nreaders < 0)
nreaders = (num_online_cpus() >> 1) + (num_online_cpus() >> 2);
if (WARN_ONCE(loops <= 0, "%s: loops = %ld, adjusted to 1\n", __func__, loops))
loops = 1;
if (WARN_ONCE(nreaders <= 0, "%s: nreaders = %d, adjusted to 1\n", __func__, nreaders))
nreaders = 1;
if (WARN_ONCE(nruns <= 0, "%s: nruns = %d, adjusted to 1\n", __func__, nruns))
nruns = 1;
reader_tasks = kcalloc(nreaders, sizeof(reader_tasks[0]),
GFP_KERNEL);
if (!reader_tasks) {
SCALEOUT_ERRSTRING("out of memory");
firsterr = -ENOMEM;
goto unwind;
}
VERBOSE_SCALEOUT("Starting %d reader threads", nreaders);
for (i = 0; i < nreaders; i++) {
init_waitqueue_head(&reader_tasks[i].wq);
firsterr = torture_create_kthread(ref_scale_reader, (void *)i,
reader_tasks[i].task);
if (torture_init_error(firsterr))
goto unwind;
}
// Main Task
init_waitqueue_head(&main_wq);
firsterr = torture_create_kthread(main_func, NULL, main_task);
if (torture_init_error(firsterr))
goto unwind;
torture_init_end();
return 0;
unwind:
torture_init_end();
ref_scale_cleanup();
if (shutdown) {
WARN_ON(!IS_MODULE(CONFIG_RCU_REF_SCALE_TEST));
kernel_power_off();
}
return firsterr;
}
module_init(ref_scale_init);
module_exit(ref_scale_cleanup);
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