linux-kernel - [PATCH tip/core/rcu 07/30] refperf: Allow decimal nanoseconds

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Date:   Mon, 22 Jun 2020 17:29:50 -0700
From:   paulmck@...nel.org
To:     rcu@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, kernel-team@...com, mingo@...nel.org,
        jiangshanlai@...il.com, dipankar@...ibm.com,
        akpm@...ux-foundation.org, mathieu.desnoyers@...icios.com,
        josh@...htriplett.org, tglx@...utronix.de, peterz@...radead.org,
        rostedt@...dmis.org, dhowells@...hat.com, edumazet@...gle.com,
        fweisbec@...il.com, oleg@...hat.com, joel@...lfernandes.org,
        "Paul E. McKenney" <paulmck@...nel.org>
Subject: [PATCH tip/core/rcu 07/30] refperf: Allow decimal nanoseconds

From: "Paul E. McKenney" <paulmck@...nel.org>

The CONFIG_PREEMPT=n rcu_read_lock()/rcu_read_unlock() pair's overhead,
even including loop overhead, is far less than one nanosecond.
Since logscale plots are not all that happy with zero values, provide
picoseconds as decimals.

Cc: Joel Fernandes (Google) <joel@...lfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@...nel.org>
---
 kernel/rcu/refperf.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/rcu/refperf.c b/kernel/rcu/refperf.c
index 57c7b7a..e991d48 100644
--- a/kernel/rcu/refperf.c
+++ b/kernel/rcu/refperf.c
@@ -375,7 +375,7 @@ static int main_func(void *arg)
 		if (torture_must_stop())
 			goto end;
 
-		reader_tasks[exp].result_avg = process_durations(exp) / ((exp + 1) * loops);
+		reader_tasks[exp].result_avg = 1000 * process_durations(exp) / ((exp + 1) * loops);
 	}
 
 	// Print the average of all experiments
@@ -386,7 +386,7 @@ static int main_func(void *arg)
 	strcat(buf, "Threads\tTime(ns)\n");
 
 	for (exp = 0; exp < nreaders; exp++) {
-		sprintf(buf1, "%d\t%llu\n", exp + 1, reader_tasks[exp].result_avg);
+		sprintf(buf1, "%d\t%llu.%03d\n", exp + 1, reader_tasks[exp].result_avg / 1000, (int)(reader_tasks[exp].result_avg % 1000));
 		strcat(buf, buf1);
 	}
 
-- 
2.9.5