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/*
* Copyright (c) 2014 Richard Braun.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
*
* This test module checks that the no-reference function of a scalable
* reference counter is actually called when the number of references drops
* to 0. An initial master thread creates a bunch of slave threads, more
* than the number of processors to enforce migrations. These slaves wait
* for the master to allocate a page for a test object with a scalable
* reference counter. Once they receive the page, they manipulate the
* counter until the master thread tells them to stop. The master thread
* also manipulates the counter for a fixed number of iterations before
* stopping the slaves. The master thread then joins all slaves to make
* sure all of them have released their reference on the test object.
* Finally, it releases the initial reference, at which point, the
* no-reference function should be called.
*
* Notes: the number of loops must be large enough to allow many epochs
* to occur.
*/
#include <errno.h>
#include <stddef.h>
#include <stdio.h>
#include <string.h>
#include <kern/condition.h>
#include <kern/init.h>
#include <kern/error.h>
#include <kern/kmem.h>
#include <kern/macros.h>
#include <kern/mutex.h>
#include <kern/panic.h>
#include <kern/sref.h>
#include <kern/syscnt.h>
#include <kern/thread.h>
#include <test/test.h>
#include <vm/vm_kmem.h>
#define NR_LOOPS (100UL * 1000 * 1000)
struct test_obj {
struct sref_counter ref_counter;
};
static struct condition test_condition;
static struct mutex test_lock;
static struct test_obj *test_obj;
static volatile int test_stop;
static void
test_manipulate_counter(struct test_obj *obj)
{
sref_counter_inc(&obj->ref_counter);
thread_yield();
sref_counter_dec(&obj->ref_counter);
thread_yield();
}
static void
test_ref(void *arg)
{
struct test_obj *obj;
(void)arg;
mutex_lock(&test_lock);
printf("waiting for page\n");
while (test_obj == NULL) {
condition_wait(&test_condition, &test_lock);
}
obj = test_obj;
mutex_unlock(&test_lock);
printf("page received, manipulate reference counter\n");
while (!test_stop) {
test_manipulate_counter(obj);
}
printf("thread exiting\n");
}
static void
test_obj_noref(struct sref_counter *counter)
{
struct test_obj *obj;
obj = structof(counter, struct test_obj, ref_counter);
vm_kmem_free(obj, sizeof(*obj));
printf("0 references, page released\n");
syscnt_info("sref_epoch");
syscnt_info("sref_dirty_zero");
syscnt_info("sref_true_zero");
}
static void
test_run(void *arg)
{
char name[THREAD_NAME_SIZE];
struct thread_attr attr;
struct thread **threads;
struct test_obj *obj;
volatile unsigned long loop;
unsigned int i, nr_threads;
int error;
(void)arg;
nr_threads = cpu_count() + 1;
threads = kmem_alloc(sizeof(*threads) * nr_threads);
if (threads == NULL) {
panic("kmem_alloc: %s", strerror(ENOMEM));
}
for (i = 0; i < nr_threads; i++) {
snprintf(name, sizeof(name), THREAD_KERNEL_PREFIX "test_ref/%u", i);
thread_attr_init(&attr, name);
error = thread_create(&threads[i], &attr, test_ref, NULL);
error_check(error, "thread_create");
}
printf("allocating page\n");
obj = vm_kmem_alloc(sizeof(*obj));
if (obj == NULL) {
panic("vm_kmem_alloc: %s", strerror(ENOMEM));
}
sref_counter_init(&obj->ref_counter, 1, NULL, test_obj_noref);
printf("page allocated, 1 reference, publishing\n");
mutex_lock(&test_lock);
test_obj = obj;
condition_broadcast(&test_condition);
mutex_unlock(&test_lock);
for (loop = 0; loop < NR_LOOPS; loop++) {
test_manipulate_counter(obj);
}
printf("stopping test, wait for threads\n");
test_stop = 1;
for (i = 0; i < nr_threads; i++) {
thread_join(threads[i]);
}
printf("releasing initial reference\n");
sref_counter_dec(&obj->ref_counter);
kmem_free(threads, sizeof(*threads) * nr_threads);
}
void __init
test_setup(void)
{
struct thread_attr attr;
struct thread *thread;
int error;
condition_init(&test_condition);
mutex_init(&test_lock);
thread_attr_init(&attr, THREAD_KERNEL_PREFIX "test_run");
thread_attr_set_detached(&attr);
error = thread_create(&thread, &attr, test_run, NULL);
error_check(error, "thread_create");
}
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