On 4/21/2016 3:09 AM, Wanpeng Li wrote:
2016-04-21 6:28 GMT+08:00 Rafael J. Wysocki <[email protected]>:
On 4/21/2016 12:24 AM, Wanpeng Li wrote:
2016-04-20 22:01 GMT+08:00 Peter Zijlstra <[email protected]>:
On Wed, Apr 20, 2016 at 02:32:35AM +0200, Rafael J. Wysocki wrote:
On Monday, April 18, 2016 01:51:24 PM Wanpeng Li wrote:
Sometimes update_curr() is called w/o tasks actually running, it is
captured by:
u64 delta_exec = rq_clock_task(rq) - curr->se.exec_start;
We should not trigger cpufreq update in this case for rt/deadline
classes, and this patch fix it.
Signed-off-by: Wanpeng Li <[email protected]>
The signed-off-by tag should agree with the From: header. One way to
achieve
that is to add an extra From: line at the start of the changelog.
That said, this looks like a good catch that should go into 4.6 to me.
Peter, what do you think?
I'm confused by the Changelog. *what* ?
Sometimes .update_curr hook is called w/o tasks actually running, it is
captured by:
u64 delta_exec = rq_clock_task(rq) - curr->se.exec_start;
We should not trigger cpufreq update in this case for rt/deadline
classes, and this patch fix it.
That's what you wrote in the changelog, no need to repeat that.
I guess Peter is asking for more details, though. I actually would like to
get some more details here too. Like an example of when the situation in
question actually happens.
I add a print to print when delta_exec is zero for rt class, something
like below:
watchdog/5-48 [005] d... 568.449095: update_curr_rt: rt
delta_exec is zero
watchdog/5-48 [005] d... 568.449104: <stack trace>
=> pick_next_task_rt
=> __schedule
=> schedule
=> smpboot_thread_fn
=> kthread
=> ret_from_fork
watchdog/5-48 [005] d... 568.449105: update_curr_rt: rt
delta_exec is zero
watchdog/5-48 [005] d... 568.449111: <stack trace>
=> put_prev_task_rt
=> pick_next_task_idle
=> __schedule
=> schedule
=> smpboot_thread_fn
=> kthread
=> ret_from_fork
watchdog/6-56 [006] d... 568.510094: update_curr_rt: rt
delta_exec is zero
watchdog/6-56 [006] d... 568.510103: <stack trace>
=> pick_next_task_rt
=> __schedule
=> schedule
=> smpboot_thread_fn
=> kthread
=> ret_from_fork
watchdog/6-56 [006] d... 568.510105: update_curr_rt: rt
delta_exec is zero
watchdog/6-56 [006] d... 568.510111: <stack trace>
=> put_prev_task_rt
=> pick_next_task_idle
=> __schedule
=> schedule
=> smpboot_thread_fn
=> kthread
=> ret_from_fork
[...]
And the statement in your changelog follows from this I suppose. How
does it follow, exactly?
Thanks,
Rafael
