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/*
* Copyright (c) 2017 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 module is a stress test of the weak reference implementation
* of scalable reference counters. Two threads are created. The first
* periodically allocates a page and initializes a counter inside the
* page, then immediately decrements the counter. The intended effect
* is to mark the counter as dying as soon as possible. The second
* thread continually attempts to obtain a reference, i.e. increment
* the counter, through a weak reference. Counters are regularly
* printed to monitor activity. There should be almost as many noref
* calls as there are iterations in the first thread (a bit lower
* because of the review delay) and a good amount of revives (at least
* on multiprocessor machines) caused by successfully getting the counter
* from the weak reference while it is marked dying but still in review.
* Iterations in the second thread may spike when obtaining a reference
* fails, because the error case is much faster and continues until the
* first thread reinitializes the weak reference.
*/
#include <stddef.h>
#include <stdio.h>
#include <kern/error.h>
#include <kern/init.h>
#include <kern/macros.h>
#include <kern/sref.h>
#include <kern/syscnt.h>
#include <kern/thread.h>
#include <test/test.h>
#include <vm/vm_kmem.h>
static struct sref_weakref test_weakref;
static void
test_noref(struct sref_counter *counter)
{
vm_kmem_free(counter, sizeof(*counter));
}
static void
test_run(void *arg)
{
struct sref_counter *counter;
volatile unsigned long j;
unsigned long i;
(void)arg;
for (i = 1; /* no condition */; i++) {
counter = vm_kmem_alloc(sizeof(*counter));
if (counter == NULL) {
continue;
}
sref_counter_init(counter, 1, &test_weakref, test_noref);
sref_counter_dec(counter);
for (j = 0; j < 0x20000000; j++);
printf("run: iterations: %lu\n", i);
syscnt_info("sref_epoch");
syscnt_info("sref_dirty_zero");
syscnt_info("sref_revive");
syscnt_info("sref_true_zero");
}
}
static void
test_ref(void *arg)
{
struct sref_counter *counter;
unsigned long i;
(void)arg;
for (i = 1; /* no condition */; i++) {
counter = sref_weakref_get(&test_weakref);
if (counter != NULL) {
sref_counter_dec(counter);
}
if ((i % 100000000) == 0) {
printf("ref: iterations: %lu\n", i);
}
}
}
void __init
test_setup(void)
{
struct thread_attr attr;
struct thread *thread;
int error;
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");
thread_attr_init(&attr, THREAD_KERNEL_PREFIX "test_ref");
thread_attr_set_detached(&attr);
error = thread_create(&thread, &attr, test_ref, NULL);
error_check(error, "thread_create");
}
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