On Thu, Aug 30, 2012 at 11:45:09AM -0700, Paul E. McKenney wrote:
> From: "Paul E. McKenney" <paul.mcken...@linaro.org>
>
> Many rcutorture runs include CPU-hotplug operations in their stress
> testing. This commit accumulates statistics on the durations of these
> operations in deference to the recent concern about the overhead and
> latency of these operations.
How many jiffies, on average, do these operations take? Measuring these
using jiffies seems highly prone to repeated rounding error.
> Signed-off-by: Paul E. McKenney <paul.mcken...@linaro.org>
> Signed-off-by: Paul E. McKenney <paul...@linux.vnet.ibm.com>
> ---
> kernel/rcutorture.c | 42 +++++++++++++++++++++++++++++++++++++-----
> 1 files changed, 37 insertions(+), 5 deletions(-)
>
> diff --git a/kernel/rcutorture.c b/kernel/rcutorture.c
> index 86315d3..c6cf6ff 100644
> --- a/kernel/rcutorture.c
> +++ b/kernel/rcutorture.c
> @@ -176,8 +176,14 @@ static long n_rcu_torture_boosts;
> static long n_rcu_torture_timers;
> static long n_offline_attempts;
> static long n_offline_successes;
> +static unsigned long sum_offline;
> +static int min_offline = -1;
> +static int max_offline;
> static long n_online_attempts;
> static long n_online_successes;
> +static unsigned long sum_online;
> +static int min_online = -1;
> +static int max_online;
> static long n_barrier_attempts;
> static long n_barrier_successes;
> static struct list_head rcu_torture_removed;
> @@ -1214,11 +1220,13 @@ rcu_torture_printk(char *page)
> n_rcu_torture_boost_failure,
> n_rcu_torture_boosts,
> n_rcu_torture_timers);
> - cnt += sprintf(&page[cnt], "onoff: %ld/%ld:%ld/%ld ",
> - n_online_successes,
> - n_online_attempts,
> - n_offline_successes,
> - n_offline_attempts);
> + cnt += sprintf(&page[cnt],
> + "onoff: %ld/%ld:%ld/%ld %d,%d:%d,%d %lu:%lu (HZ=%d) ",
> + n_online_successes, n_online_attempts,
> + n_offline_successes, n_offline_attempts,
> + min_online, max_online,
> + min_offline, max_offline,
> + sum_online, sum_offline, HZ);
> cnt += sprintf(&page[cnt], "barrier: %ld/%ld:%ld",
> n_barrier_successes,
> n_barrier_attempts,
> @@ -1490,8 +1498,10 @@ static int __cpuinit
> rcu_torture_onoff(void *arg)
> {
> int cpu;
> + unsigned long delta;
> int maxcpu = -1;
> DEFINE_RCU_RANDOM(rand);
> + unsigned long starttime;
>
> VERBOSE_PRINTK_STRING("rcu_torture_onoff task started");
> for_each_online_cpu(cpu)
> @@ -1509,6 +1519,7 @@ rcu_torture_onoff(void *arg)
> printk(KERN_ALERT "%s" TORTURE_FLAG
> "rcu_torture_onoff task: offlining %d\n",
> torture_type, cpu);
> + starttime = jiffies;
> n_offline_attempts++;
> if (cpu_down(cpu) == 0) {
> if (verbose)
> @@ -1516,12 +1527,23 @@ rcu_torture_onoff(void *arg)
> "rcu_torture_onoff task:
> offlined %d\n",
> torture_type, cpu);
> n_offline_successes++;
> + delta = jiffies - starttime;
> + sum_offline += delta;
> + if (min_offline < 0) {
> + min_offline = delta;
> + max_offline = delta;
> + }
> + if (min_offline > delta)
> + min_offline = delta;
> + if (max_offline < delta)
> + max_offline = delta;
> }
> } else if (cpu_is_hotpluggable(cpu)) {
> if (verbose)
> printk(KERN_ALERT "%s" TORTURE_FLAG
> "rcu_torture_onoff task: onlining %d\n",
> torture_type, cpu);
> + starttime = jiffies;
> n_online_attempts++;
> if (cpu_up(cpu) == 0) {
> if (verbose)
> @@ -1529,6 +1551,16 @@ rcu_torture_onoff(void *arg)
> "rcu_torture_onoff task: onlined
> %d\n",
> torture_type, cpu);
> n_online_successes++;
> + delta = jiffies - starttime;
> + sum_online += delta;
> + if (min_online < 0) {
> + min_online = delta;
> + max_online = delta;
> + }
> + if (min_online > delta)
> + min_online = delta;
> + if (max_online < delta)
> + max_online = delta;
> }
> }
> schedule_timeout_interruptible(onoff_interval * HZ);
> --
> 1.7.8
>
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