On Fri, Mar 25, 2022 at 04:18:19PM -0400, Steven Rostedt wrote:
> On Fri, 25 Mar 2022 19:36:24 +0000
> John Keeping <john@xxxxxxxxxxxx> wrote:
>
> > On Wed, Mar 23, 2022 at 10:57:17PM -0400, Steven Rostedt wrote:
> > > From: "Steven Rostedt (Google)" <rostedt@xxxxxxxxxxx>
> > >
> > > Display for each CPU that was traced, the amount of time tasks ran on
> > > them. Listing the tasks from the longest runner to the least.
> > >
> > > Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
> > > ---
> > > + for (i = 0; i < nr_tasks; i++) {
> > > + task = cpu_tasks[i]->task;
> > > +
> > > + if (!i) {
> > > + printf(" Task name PID \t Run time\n");
> > > + printf(" --------- --- \t --------\n");
> > > + }
> > > + printf("%16s %8d\t",
> > > + tep_data_comm_from_pid(tep, task->pid),
> > > + task->pid);
> > > + print_time(cpu_tasks[i]->runtime, '_');
> > > + printf(" (%%%lld)\n", (task->runtime * 100) / total_time);
> >
> > Is there a reason for using the CPU-specific runtime for the value and
> > the total runtime for the percentage?
> >
> > I expected the percentage to be the percentage of this CPU's time spend
> > running the task.
>
> We modify it so that each CPU has the same run time, unless there's missed
> events at the start (later patches), and then we change total_time to be
> the total time of the events on the CPU and not the entire trace.
I think we're talking about different things here, I probably wasn't
entirely clear about this. It's the numerator of this division that I'm
concerned about and I wonder if this should be:
(cpu_tasks[i]->runtime * 100) / total_time
If total_time is 10 seconds and there's a task A which runs on CPU0 for
2 seconds and CPU1 for 1 second then I expect to see:
CPU 0
A 2.000 (20%)
CPU 1
A 1.000 (10%)
But at the moment both of those lines will give 30% (although the actual
run times are correct).
