high resolution timers and timer interrupt thrashing

high resolution timers and timer interrupt thrashing

[Sudharsan Vijayaraghavan]

Hi All,

With CONFIG_HIGH_RES_TIMERS configured and a whole lot of timer_create with
interval of less than jiffy (i.e., few nano seconds) we are bound to
get timer interrupts
less than a jiffy because set_next_event will configure for expires
less than jiffy.

This means we are thrashing the system with more timer interrupts,
perhaps to extent
of almost every clock tick, is my understanding correct?

Given this is it not dangerous to configure CONFIG_HIGH_RES_TIMERS
Please give your thoughts

Thanks,
Sudharsan

high resolution timers and timer interrupt thrashing

[Sudharsan vijayaraghavan]

Hi All,

With CONFIG_HIGH_RES_TIMERS configured and a whole lot of timer_create with
interval of less than jiffy (i.e., few nano seconds) we are bound to
get timer interrupts
less than a jiffy because set_next_event will configure for expires
less than jiffy.

This means we are thrashing the system with more timer interrupts,
perhaps to extent
of almost every clock tick, is my understanding correct?

Given this is it not dangerous to configure CONFIG_HIGH_RES_TIMERS
Please give your thoughts

Thanks,
Sudharsan
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.kernelnewbies.org/pipermail/kernelnewbies/attachments/20140421/b4aeee54/attachment-0001.html 

high resolution timers and timer interrupt thrashing

[bill4carson]

On 2014?04?21? 01:54, Sudharsan Vijayaraghavan wrote:
> Hi All,
>
> With CONFIG_HIGH_RES_TIMERS configured and a whole lot of timer_create with
> interval of less than jiffy (i.e., few nano seconds) we are bound to
> get timer interrupts
> less than a jiffy because set_next_event will configure for expires
> less than jiffy.
>
> This means we are thrashing the system with more timer interrupts,
> perhaps to extent
> of almost every clock tick, is my understanding correct?

Yes, with hrtimer enabled, timer interrupt could be more frequently ever than before.
The effort of hrtimer is to enable high resolution timing for user land application
like video/audio like wise.

You can google why hrtimer was made to solve what kind of problem.

> Given this is it not dangerous to configure CONFIG_HIGH_RES_TIMERS
> Please give your thoughts
>
> Thanks,
> Sudharsan
>
> _______________________________________________
> Kernelnewbies mailing list
> Kernelnewbies at kernelnewbies.org
> http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
>

-- 
?????????,??????????

--bill