Re: [PATCH 1/3] rcu: Use static initializer for krc.lock

[Uladzislau Rezki <urezki@gmail.com>]

> Uladzislau Rezki <urezki@gmail.com> wrote:
> 
> > <snip>
> > root@pc636:/sys/kernel/debug/tracing# cat set_ftrace_filter
> > measure_schedule_delayed_work.constprop.86
> > root@pc636:/sys/kernel/debug/tracing# cat tracing_thresh
> > 5
> > root@pc636:/sys/kernel/debug/tracing# cat current_tracer
> > function_graph
> > root@pc636:/sys/kernel/debug/tracing#
> > <snip>
> > 
> > Also i set 5 microseconds threshold to filter out what is less
> > and added the latency-format trace option.
> 
> Ah, I forgot that tracing_thresh affects function graph tracing.
> 
> The tracing infrastructure has so many features, I can't even keep up ;-)
> 
No problem :)

BTW, i decided to perform manual measurement of the schedule_delayed_work()
duration, just in case:

test PC: laptop with Intel(R) Core(TM) i5-3320M CPU @ 2.60GHz

<snip>
static void noinline
measure_schedule_delayed_work(struct kfree_rcu_cpu *krcp)
{
       u64 delta;

       delta = sched_clock();
       schedule_delayed_work(&krcp->monitor_work, KFREE_DRAIN_JIFFIES);
       delta = sched_clock() - delta;

       if (delta > 100)
               trace_printk("-> took %llu nanoseconds.\n", delta);
}
<snip>

I get the following figures of taken time:

MEDIAN: 831 nanoseconds
MAX: 4423 nanoseconds
MIN: 123 nanoseconds

The data you can find here: ftp://vps418301.ovh.net/incoming/measure_schedule_delayed_work.txt

--
Vlad Rezki