reboot_cpu is s[mp]#### with #### being the processor
to be used for rebooting.
- refperf.holdoff= [KNL]
+ refscale.holdoff= [KNL]
Set test-start holdoff period. The purpose of
this parameter is to delay the start of the
test until boot completes in order to avoid
interference.
- refperf.loops= [KNL]
+ refscale.loops= [KNL]
Set the number of loops over the synchronization
primitive under test. Increasing this number
reduces noise due to loop start/end overhead,
noise to a handful of picoseconds on ca. 2020
x86 laptops.
- refperf.nreaders= [KNL]
+ refscale.nreaders= [KNL]
Set number of readers. The default value of -1
selects N, where N is roughly 75% of the number
of CPUs. A value of zero is an interesting choice.
- refperf.nruns= [KNL]
+ refscale.nruns= [KNL]
Set number of runs, each of which is dumped onto
the console log.
- refperf.readdelay= [KNL]
+ refscale.readdelay= [KNL]
Set the read-side critical-section duration,
measured in microseconds.
- refperf.shutdown= [KNL]
+ refscale.scale_type= [KNL]
+ Specify the read-protection implementation to test.
+
+ refscale.shutdown= [KNL]
Shut down the system at the end of the performance
test. This defaults to 1 (shut it down) when
rcuperf is built into the kernel and to 0 (leave
it running) when rcuperf is built as a module.
- refperf.verbose= [KNL]
+ refscale.verbose= [KNL]
Enable additional printk() statements.
relax_domain_level=
obj-$(CONFIG_TINY_SRCU) += srcutiny.o
obj-$(CONFIG_RCU_TORTURE_TEST) += rcutorture.o
obj-$(CONFIG_RCU_PERF_TEST) += rcuperf.o
-obj-$(CONFIG_RCU_REF_SCALE_TEST) += refperf.o
+obj-$(CONFIG_RCU_REF_SCALE_TEST) += refscale.o
obj-$(CONFIG_TREE_RCU) += tree.o
obj-$(CONFIG_TINY_RCU) += tiny.o
obj-$(CONFIG_RCU_NEED_SEGCBLIST) += rcu_segcblist.o
+++ /dev/null
-// 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 <joel@joelfernandes.org>
-
-#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/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 PERF_FLAG "-ref-perf: "
-
-#define PERFOUT(s, x...) \
- pr_alert("%s" PERF_FLAG s, perf_type, ## x)
-
-#define VERBOSE_PERFOUT(s, x...) \
- do { if (verbose) pr_alert("%s" PERF_FLAG s, perf_type, ## x); } while (0)
-
-#define VERBOSE_PERFOUT_ERRSTRING(s, x...) \
- do { if (verbose) pr_alert("%s" PERF_FLAG "!!! " s, perf_type, ## x); } while (0)
-
-MODULE_LICENSE("GPL");
-MODULE_AUTHOR("Joel Fernandes (Google) <joel@joelfernandes.org>");
-
-static char *perf_type = "rcu";
-module_param(perf_type, charp, 0444);
-MODULE_PARM_DESC(perf_type, "Type of test (rcu, srcu, refcnt, rwsem, rwlock.");
-
-torture_param(int, verbose, 0, "Enable 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 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 REFPERF_SHUTDOWN 0
-#else
-# define REFPERF_SHUTDOWN 1
-#endif
-
-torture_param(bool, shutdown, REFPERF_SHUTDOWN,
- "Shutdown at end of performance 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_perf_ops {
- void (*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 struct ref_perf_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 void rcu_sync_perf_init(void)
-{
-}
-
-static struct ref_perf_ops rcu_ops = {
- .init = rcu_sync_perf_init,
- .readsection = ref_rcu_read_section,
- .delaysection = ref_rcu_delay_section,
- .name = "rcu"
-};
-
-// Definitions for SRCU ref perf testing.
-DEFINE_STATIC_SRCU(srcu_refctl_perf);
-static struct srcu_struct *srcu_ctlp = &srcu_refctl_perf;
-
-static void srcu_ref_perf_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_perf_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 struct ref_perf_ops srcu_ops = {
- .init = rcu_sync_perf_init,
- .readsection = srcu_ref_perf_read_section,
- .delaysection = srcu_ref_perf_delay_section,
- .name = "srcu"
-};
-
-// Definitions for RCU Tasks ref perf testing: Empty read markers.
-// These definitions also work for RCU Rude readers.
-static void rcu_tasks_ref_perf_read_section(const int nloops)
-{
- int i;
-
- for (i = nloops; i >= 0; i--)
- continue;
-}
-
-static void rcu_tasks_ref_perf_delay_section(const int nloops, const int udl, const int ndl)
-{
- int i;
-
- for (i = nloops; i >= 0; i--)
- un_delay(udl, ndl);
-}
-
-static struct ref_perf_ops rcu_tasks_ops = {
- .init = rcu_sync_perf_init,
- .readsection = rcu_tasks_ref_perf_read_section,
- .delaysection = rcu_tasks_ref_perf_delay_section,
- .name = "rcu-tasks"
-};
-
-// Definitions for RCU Tasks Trace ref perf testing.
-static void rcu_trace_ref_perf_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_perf_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 struct ref_perf_ops rcu_trace_ops = {
- .init = rcu_sync_perf_init,
- .readsection = rcu_trace_ref_perf_read_section,
- .delaysection = rcu_trace_ref_perf_delay_section,
- .name = "rcu-trace"
-};
-
-// 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 struct ref_perf_ops refcnt_ops = {
- .init = rcu_sync_perf_init,
- .readsection = ref_refcnt_section,
- .delaysection = ref_refcnt_delay_section,
- .name = "refcnt"
-};
-
-// Definitions for rwlock
-static rwlock_t test_rwlock;
-
-static void ref_rwlock_init(void)
-{
- rwlock_init(&test_rwlock);
-}
-
-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 struct ref_perf_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 void ref_rwsem_init(void)
-{
- init_rwsem(&test_rwsem);
-}
-
-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 struct ref_perf_ops rwsem_ops = {
- .init = ref_rwsem_init,
- .readsection = ref_rwsem_section,
- .delaysection = ref_rwsem_delay_section,
- .name = "rwsem"
-};
-
-static void rcu_perf_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_perf_reader(void *arg)
-{
- unsigned long flags;
- long me = (long)arg;
- struct reader_task *rt = &(reader_tasks[me]);
- u64 start;
- s64 duration;
-
- VERBOSE_PERFOUT("ref_perf_reader %ld: task started", me);
- 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_PERFOUT("ref_perf_reader %ld: waiting to start next experiment on cpu %d", me, 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(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_PERFOUT("ref_perf_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_perf_one_reader();
- if (!atomic_dec_return(&n_warmedup))
- while (atomic_read_acquire(&n_warmedup))
- rcu_perf_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_perf_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_perf_one_reader();
-
- if (atomic_dec_and_test(&nreaders_exp))
- wake_up(&main_wq);
-
- VERBOSE_PERFOUT("ref_perf_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_perf_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;
- char buf1[64];
- char *buf;
- u64 sum = 0;
-
- buf = kmalloc(128 + nreaders * 32, GFP_KERNEL);
- if (!buf)
- return 0;
- buf[0] = 0;
- sprintf(buf, "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]);
- sprintf(buf1, "%d: %llu\t", i, rt->last_duration_ns);
-
- if (i % 5 == 0)
- strcat(buf, "\n");
- strcat(buf, buf1);
-
- sum += rt->last_duration_ns;
- }
- strcat(buf, "\n");
-
- PERFOUT("%s\n", buf);
-
- 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)
-{
- bool errexit = false;
- 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_PERFOUT("main_func task started");
- result_avg = kzalloc(nruns * sizeof(*result_avg), GFP_KERNEL);
- buf = kzalloc(64 + nruns * 32, GFP_KERNEL);
- if (!result_avg || !buf) {
- VERBOSE_PERFOUT_ERRSTRING("out of memory");
- errexit = true;
- }
- 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 (errexit)
- break;
- 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_PERFOUT("main_func: experiment started, waiting for %d readers",
- nreaders);
-
- wait_event(main_wq,
- !atomic_read(&nreaders_exp) || torture_must_stop());
-
- VERBOSE_PERFOUT("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
- PERFOUT("END OF TEST. Calculating average duration per loop (nanoseconds)...\n");
-
- buf[0] = 0;
- strcat(buf, "\n");
- strcat(buf, "Runs\tTime(ns)\n");
-
- for (exp = 0; exp < nruns; exp++) {
- u64 avg;
- u32 rem;
-
- if (errexit)
- break;
- avg = div_u64_rem(result_avg[exp], 1000, &rem);
- sprintf(buf1, "%d\t%llu.%03u\n", exp + 1, avg, rem);
- strcat(buf, buf1);
- }
-
- if (!errexit)
- PERFOUT("%s", buf);
-
- // 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_perf_print_module_parms(struct ref_perf_ops *cur_ops, const char *tag)
-{
- pr_alert("%s" PERF_FLAG
- "--- %s: verbose=%d shutdown=%d holdoff=%d loops=%ld nreaders=%d nruns=%d readdelay=%d\n", perf_type, tag,
- verbose, shutdown, holdoff, loops, nreaders, nruns, readdelay);
-}
-
-static void
-ref_perf_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_perf_reader",
- reader_tasks[i].task);
- }
- kfree(reader_tasks);
-
- torture_stop_kthread("main_task", main_task);
- kfree(main_task);
-
- // Do perf-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_perf_shutdown(void *arg)
-{
- wait_event(shutdown_wq, shutdown_start);
-
- smp_mb(); // Wake before output.
- ref_perf_cleanup();
- kernel_power_off();
-
- return -EINVAL;
-}
-
-static int __init
-ref_perf_init(void)
-{
- long i;
- int firsterr = 0;
- static struct ref_perf_ops *perf_ops[] = {
- &rcu_ops, &srcu_ops, &rcu_trace_ops, &rcu_tasks_ops,
- &refcnt_ops, &rwlock_ops, &rwsem_ops,
- };
-
- if (!torture_init_begin(perf_type, verbose))
- return -EBUSY;
-
- for (i = 0; i < ARRAY_SIZE(perf_ops); i++) {
- cur_ops = perf_ops[i];
- if (strcmp(perf_type, cur_ops->name) == 0)
- break;
- }
- if (i == ARRAY_SIZE(perf_ops)) {
- pr_alert("rcu-perf: invalid perf type: \"%s\"\n", perf_type);
- pr_alert("rcu-perf types:");
- for (i = 0; i < ARRAY_SIZE(perf_ops); i++)
- pr_cont(" %s", perf_ops[i]->name);
- pr_cont("\n");
- WARN_ON(!IS_MODULE(CONFIG_RCU_REF_SCALE_TEST));
- firsterr = -EINVAL;
- cur_ops = NULL;
- goto unwind;
- }
- if (cur_ops->init)
- cur_ops->init();
-
- ref_perf_print_module_parms(cur_ops, "Start of test");
-
- // Shutdown task
- if (shutdown) {
- init_waitqueue_head(&shutdown_wq);
- firsterr = torture_create_kthread(ref_perf_shutdown, NULL,
- shutdown_task);
- if (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);
- reader_tasks = kcalloc(nreaders, sizeof(reader_tasks[0]),
- GFP_KERNEL);
- if (!reader_tasks) {
- VERBOSE_PERFOUT_ERRSTRING("out of memory");
- firsterr = -ENOMEM;
- goto unwind;
- }
-
- VERBOSE_PERFOUT("Starting %d reader threads\n", nreaders);
-
- for (i = 0; i < nreaders; i++) {
- firsterr = torture_create_kthread(ref_perf_reader, (void *)i,
- reader_tasks[i].task);
- if (firsterr)
- goto unwind;
-
- init_waitqueue_head(&(reader_tasks[i].wq));
- }
-
- // Main Task
- init_waitqueue_head(&main_wq);
- firsterr = torture_create_kthread(main_func, NULL, main_task);
- if (firsterr)
- goto unwind;
-
- torture_init_end();
- return 0;
-
-unwind:
- torture_init_end();
- ref_perf_cleanup();
- return firsterr;
-}
-
-module_init(ref_perf_init);
-module_exit(ref_perf_cleanup);
--- /dev/null
+// 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 <joel@joelfernandes.org>
+
+#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/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, scale_type, ## x); } while (0)
+
+#define VERBOSE_SCALEOUT_ERRSTRING(s, x...) \
+ do { if (verbose) pr_alert("%s" SCALE_FLAG "!!! " s, scale_type, ## x); } while (0)
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Joel Fernandes (Google) <joel@joelfernandes.org>");
+
+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");
+
+// 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 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 {
+ void (*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 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 void rcu_sync_scale_init(void)
+{
+}
+
+static 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 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"
+};
+
+// 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 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"
+};
+
+// 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 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"
+};
+
+// 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 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 void ref_rwlock_init(void)
+{
+ rwlock_init(&test_rwlock);
+}
+
+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 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 void ref_rwsem_init(void)
+{
+ init_rwsem(&test_rwsem);
+}
+
+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 struct ref_scale_ops rwsem_ops = {
+ .init = ref_rwsem_init,
+ .readsection = ref_rwsem_section,
+ .delaysection = ref_rwsem_delay_section,
+ .name = "rwsem"
+};
+
+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("ref_scale_reader %ld: task started", me);
+ 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("ref_scale_reader %ld: waiting to start next experiment on cpu %d", me, 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(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("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("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;
+ char buf1[64];
+ char *buf;
+ u64 sum = 0;
+
+ buf = kmalloc(128 + nreaders * 32, GFP_KERNEL);
+ if (!buf)
+ return 0;
+ buf[0] = 0;
+ sprintf(buf, "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]);
+ sprintf(buf1, "%d: %llu\t", i, rt->last_duration_ns);
+
+ if (i % 5 == 0)
+ strcat(buf, "\n");
+ strcat(buf, buf1);
+
+ sum += rt->last_duration_ns;
+ }
+ strcat(buf, "\n");
+
+ SCALEOUT("%s\n", buf);
+
+ 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)
+{
+ bool errexit = false;
+ 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(64 + nruns * 32, GFP_KERNEL);
+ if (!result_avg || !buf) {
+ VERBOSE_SCALEOUT_ERRSTRING("out of memory");
+ errexit = true;
+ }
+ 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 (errexit)
+ break;
+ 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");
+
+ buf[0] = 0;
+ strcat(buf, "\n");
+ strcat(buf, "Runs\tTime(ns)\n");
+
+ for (exp = 0; exp < nruns; exp++) {
+ u64 avg;
+ u32 rem;
+
+ if (errexit)
+ break;
+ avg = div_u64_rem(result_avg[exp], 1000, &rem);
+ sprintf(buf1, "%d\t%llu.%03u\n", exp + 1, avg, rem);
+ strcat(buf, buf1);
+ }
+
+ if (!errexit)
+ SCALEOUT("%s", buf);
+
+ // 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(struct ref_scale_ops *cur_ops, const char *tag)
+{
+ pr_alert("%s" SCALE_FLAG
+ "--- %s: verbose=%d shutdown=%d holdoff=%d loops=%ld nreaders=%d nruns=%d readdelay=%d\n", scale_type, tag,
+ verbose, shutdown, holdoff, 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(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 struct ref_scale_ops *scale_ops[] = {
+ &rcu_ops, &srcu_ops, &rcu_trace_ops, &rcu_tasks_ops,
+ &refcnt_ops, &rwlock_ops, &rwsem_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");
+ WARN_ON(!IS_MODULE(CONFIG_RCU_REF_SCALE_TEST));
+ firsterr = -EINVAL;
+ cur_ops = NULL;
+ goto unwind;
+ }
+ if (cur_ops->init)
+ cur_ops->init();
+
+ 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 (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);
+ reader_tasks = kcalloc(nreaders, sizeof(reader_tasks[0]),
+ GFP_KERNEL);
+ if (!reader_tasks) {
+ VERBOSE_SCALEOUT_ERRSTRING("out of memory");
+ firsterr = -ENOMEM;
+ goto unwind;
+ }
+
+ VERBOSE_SCALEOUT("Starting %d reader threads\n", nreaders);
+
+ for (i = 0; i < nreaders; i++) {
+ firsterr = torture_create_kthread(ref_scale_reader, (void *)i,
+ reader_tasks[i].task);
+ if (firsterr)
+ goto unwind;
+
+ init_waitqueue_head(&(reader_tasks[i].wq));
+ }
+
+ // Main Task
+ init_waitqueue_head(&main_wq);
+ firsterr = torture_create_kthread(main_func, NULL, main_task);
+ if (firsterr)
+ goto unwind;
+
+ torture_init_end();
+ return 0;
+
+unwind:
+ torture_init_end();
+ ref_scale_cleanup();
+ return firsterr;
+}
+
+module_init(ref_scale_init);
+module_exit(ref_scale_cleanup);
#
# Adds per-version torture-module parameters to kernels supporting them.
per_version_boot_params () {
- echo $1 refperf.shutdown=1 \
- refperf.verbose=1
+ echo $1 refscale.shutdown=1 \
+ refscale.verbose=1
}
projects / linux-block.git / commitdiff