Re: [PATCH] Call get_time() only when necessary in run_hrtimer_queue

[Andrew Morton <akpm@osdl.org>]

Dimitri Sivanich <sivanich@sgi.com> wrote:
>
> It seems that run_hrtimer_queue() is calling get_time() much more often
> than it needs to.
> 
> With this patch, it only calls get_time() if there's a pending timer.
> 
> Following is from a profile done without the patch:
> kernel ticks:           30841           1.02 %
>       13572       44.01    44.01      time_interpolator_get_offset
>         155        0.50    96.91      hrtimer_run_queues
> 
> And with the patch:
> 	kernel ticks:           18334           0.58 %
>          74        0.40    97.81      hrtimer_run_queues
>          43        0.23    98.63      time_interpolator_get_offset
> 
> 

This code has been extensively redone in -mm and I am planning on sending
all that to Linus within a week.

The hrtimer rework in -mm might fix this performance problem, although from
a quick peek, perhaps not.

So could you please verify that the problem still needs fixing in
2.6.16-mm1 and if so, raise a patch against that?

Thanks.