refperf: Add read-side delay module parameter
This commit adds a refperf.readdelay module parameter that controls the duration of each critical section. This parameter allows gathering data showing how the performance differences between the various primitives vary with critical-section length. Cc: Joel Fernandes (Google) <joel@joelfernandes.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit is contained in:
Paul E. McKenney
parent
96af866959
commit
b4d1e34f65
@ -66,8 +66,8 @@ torture_param(long, loops, 10000000, "Number of loops per experiment.");
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torture_param(int, nreaders, -1, "Number of readers, -1 for 75% of CPUs.");
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// Number of runs.
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torture_param(int, nruns, 30, "Number of experiments to run.");
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// Reader delay in nanoseconds, 0 for no delay.
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torture_param(int, readdelay, 0, "Read-side delay in nanoseconds.");
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// Reader delay in microseconds, 0 for no delay.
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torture_param(int, readdelay, 0, "Read-side delay in microseconds.");
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#ifdef MODULE
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# define REFPERF_SHUTDOWN 0
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@ -111,6 +111,7 @@ struct ref_perf_ops {
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void (*init)(void);
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void (*cleanup)(void);
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void (*readsection)(const int nloops);
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void (*delaysection)(const int nloops, const int ndelay);
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const char *name;
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};
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@ -126,6 +127,17 @@ static void ref_rcu_read_section(const int nloops)
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}
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}
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static void ref_rcu_delay_section(const int nloops, const int ndelay)
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{
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int i;
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for (i = nloops; i >= 0; i--) {
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rcu_read_lock();
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udelay(ndelay);
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rcu_read_unlock();
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}
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}
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static void rcu_sync_perf_init(void)
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{
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}
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@ -133,6 +145,7 @@ static void rcu_sync_perf_init(void)
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static struct ref_perf_ops rcu_ops = {
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.init = rcu_sync_perf_init,
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.readsection = ref_rcu_read_section,
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.delaysection = ref_rcu_delay_section,
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.name = "rcu"
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};
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@ -141,7 +154,7 @@ static struct ref_perf_ops rcu_ops = {
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DEFINE_STATIC_SRCU(srcu_refctl_perf);
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static struct srcu_struct *srcu_ctlp = &srcu_refctl_perf;
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static void srcu_ref_perf_read_section(int nloops)
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static void srcu_ref_perf_read_section(const int nloops)
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{
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int i;
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int idx;
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@ -152,16 +165,29 @@ static void srcu_ref_perf_read_section(int nloops)
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}
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}
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static void srcu_ref_perf_delay_section(const int nloops, const int ndelay)
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{
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int i;
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int idx;
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for (i = nloops; i >= 0; i--) {
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idx = srcu_read_lock(srcu_ctlp);
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udelay(ndelay);
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srcu_read_unlock(srcu_ctlp, idx);
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}
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}
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static struct ref_perf_ops srcu_ops = {
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.init = rcu_sync_perf_init,
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.readsection = srcu_ref_perf_read_section,
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.delaysection = srcu_ref_perf_delay_section,
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.name = "srcu"
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};
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// Definitions for reference count
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static atomic_t refcnt;
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static void ref_perf_refcnt_section(const int nloops)
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static void ref_refcnt_section(const int nloops)
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{
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int i;
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@ -171,21 +197,33 @@ static void ref_perf_refcnt_section(const int nloops)
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}
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}
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static void ref_refcnt_delay_section(const int nloops, const int ndelay)
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{
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int i;
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for (i = nloops; i >= 0; i--) {
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atomic_inc(&refcnt);
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udelay(ndelay);
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atomic_dec(&refcnt);
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}
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}
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static struct ref_perf_ops refcnt_ops = {
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.init = rcu_sync_perf_init,
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.readsection = ref_perf_refcnt_section,
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.readsection = ref_refcnt_section,
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.delaysection = ref_refcnt_delay_section,
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.name = "refcnt"
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};
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// Definitions for rwlock
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static rwlock_t test_rwlock;
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static void ref_perf_rwlock_init(void)
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static void ref_rwlock_init(void)
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{
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rwlock_init(&test_rwlock);
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}
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static void ref_perf_rwlock_section(const int nloops)
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static void ref_rwlock_section(const int nloops)
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{
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int i;
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@ -195,21 +233,33 @@ static void ref_perf_rwlock_section(const int nloops)
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}
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}
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static void ref_rwlock_delay_section(const int nloops, const int ndelay)
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{
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int i;
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for (i = nloops; i >= 0; i--) {
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read_lock(&test_rwlock);
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udelay(ndelay);
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read_unlock(&test_rwlock);
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}
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}
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static struct ref_perf_ops rwlock_ops = {
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.init = ref_perf_rwlock_init,
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.readsection = ref_perf_rwlock_section,
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.init = ref_rwlock_init,
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.readsection = ref_rwlock_section,
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.delaysection = ref_rwlock_delay_section,
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.name = "rwlock"
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};
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// Definitions for rwsem
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static struct rw_semaphore test_rwsem;
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static void ref_perf_rwsem_init(void)
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static void ref_rwsem_init(void)
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{
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init_rwsem(&test_rwsem);
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}
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static void ref_perf_rwsem_section(const int nloops)
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static void ref_rwsem_section(const int nloops)
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{
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int i;
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@ -219,12 +269,32 @@ static void ref_perf_rwsem_section(const int nloops)
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}
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}
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static void ref_rwsem_delay_section(const int nloops, const int ndelay)
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{
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int i;
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for (i = nloops; i >= 0; i--) {
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down_read(&test_rwsem);
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udelay(ndelay);
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up_read(&test_rwsem);
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}
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}
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static struct ref_perf_ops rwsem_ops = {
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.init = ref_perf_rwsem_init,
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.readsection = ref_perf_rwsem_section,
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.init = ref_rwsem_init,
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.readsection = ref_rwsem_section,
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.delaysection = ref_rwsem_delay_section,
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.name = "rwsem"
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};
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static void rcu_perf_one_reader(void)
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{
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if (readdelay <= 0)
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cur_ops->readsection(loops);
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else
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cur_ops->delaysection(loops, readdelay);
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}
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// Reader kthread. Repeatedly does empty RCU read-side
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// critical section, minimizing update-side interference.
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static int
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@ -265,16 +335,16 @@ repeat:
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// To reduce noise, do an initial cache-warming invocation, check
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// in, and then keep warming until everyone has checked in.
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cur_ops->readsection(loops);
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rcu_perf_one_reader();
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if (!atomic_dec_return(&n_warmedup))
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while (atomic_read_acquire(&n_warmedup))
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cur_ops->readsection(loops);
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rcu_perf_one_reader();
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// Also keep interrupts disabled. This also has the effect
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// of preventing entries into slow path for rcu_read_unlock().
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local_irq_save(flags);
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start = ktime_get_mono_fast_ns();
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cur_ops->readsection(loops);
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rcu_perf_one_reader();
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duration = ktime_get_mono_fast_ns() - start;
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local_irq_restore(flags);
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@ -284,7 +354,7 @@ repeat:
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// everyone is done.
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if (!atomic_dec_return(&n_cooleddown))
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while (atomic_read_acquire(&n_cooleddown))
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cur_ops->readsection(loops);
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rcu_perf_one_reader();
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if (atomic_dec_and_test(&nreaders_exp))
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wake_up(&main_wq);
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@ -449,8 +519,8 @@ static void
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ref_perf_print_module_parms(struct ref_perf_ops *cur_ops, const char *tag)
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{
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pr_alert("%s" PERF_FLAG
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"--- %s: verbose=%d shutdown=%d holdoff=%d loops=%ld nreaders=%d nruns=%d\n", perf_type, tag,
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verbose, shutdown, holdoff, loops, nreaders, nruns);
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"--- %s: verbose=%d shutdown=%d holdoff=%d loops=%ld nreaders=%d nruns=%d readdelay=%d\n", perf_type, tag,
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verbose, shutdown, holdoff, loops, nreaders, nruns, readdelay);
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}
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static void
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