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rcuscale: Add guest_os_delay module parameter

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This commit adds a guest_os_delay module parameter that extends warm-up
and cool-down the specified number of seconds before and after the series
of test runs.  This allows the data-collection intervals from any given
rcuscale guest OSes to line up with active periods in the other rcuscale
guest OSes, and also allows the thermal warm-up period required to obtain
consistent results from one test to the next.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Neeraj Upadhyay <Neeraj.Upadhyay@amd.com>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
This commit is contained in:
Paul E. McKenney 2024-10-09 11:02:52 -07:00 committed by Frederic Weisbecker
parent 046c06f5ba
commit ff9ba8db87
1 changed files with 17 additions and 0 deletions
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17
kernel/rcu/refscale.c
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@ -75,6 +75,9 @@ 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");
// Number of seconds to extend warm-up and cool-down for multiple guest OSes
torture_param(long, guest_os_delay, 0,
"Number of seconds to extend warm-up/cool-down for multiple guest OSes.");
// 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)");
@ -801,6 +804,18 @@ static void rcu_scale_one_reader(void)
cur_ops->delaysection(loops, readdelay / 1000, readdelay % 1000);
}
// Warm up cache, or, if needed run a series of rcu_scale_one_reader()
// to allow multiple rcuscale guest OSes to collect mutually valid data.
static void rcu_scale_warm_cool(void)
{
unsigned long jdone = jiffies + (guest_os_delay > 0 ? guest_os_delay * HZ : -1);
do {
rcu_scale_one_reader();
cond_resched();
} while (time_before(jiffies, jdone));
}
// Reader kthread. Repeatedly does empty RCU read-side
// critical section, minimizing update-side interference.
static int
@ -957,6 +972,7 @@ static int main_func(void *arg)
schedule_timeout_uninterruptible(1);
// Start exp readers up per experiment
rcu_scale_warm_cool();
for (exp = 0; exp < nruns && !torture_must_stop(); exp++) {
if (torture_must_stop())
goto end;
@ -987,6 +1003,7 @@ static int main_func(void *arg)
result_avg[exp] = div_u64(1000 * process_durations(nreaders), nreaders * loops);
}
rcu_scale_warm_cool();
// Print the average of all experiments
SCALEOUT("END OF TEST. Calculating average duration per loop (nanoseconds)...\n");