Re: [Intel-gfx] [PATCH 4/4] cpuidle: Hack iowait weighting to avoid C-state reduction for graphics.

[ykzhao <yakui.zhao@intel.com>]

On Tue, 2010-11-02 at 04:23 +0800, Eric Anholt wrote:
> Improves nexuiz performance by about 1% on my system.

CC: Arjan and linux-acpi mailing list.

It seems that the selection of C-state will become very sensitive to IO
wait after the multi factor is changed from 10 to 1000.
Maybe only one IO/wait will bring that the system can't enter the deep
C-state.
> 
> Signed-off-by: Eric Anholt <eric@anholt.net>
> ---
>  drivers/cpuidle/governors/menu.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c
> index f508690..9bb5654 100644
> --- a/drivers/cpuidle/governors/menu.c
> +++ b/drivers/cpuidle/governors/menu.c
> @@ -175,7 +175,7 @@ static inline int performance_multiplier(void)
>  	mult += 2 * get_loadavg();
>  
>  	/* for IO wait tasks (per cpu!) we add 5x each */
> -	mult += 10 * nr_iowait_cpu(smp_processor_id());
> +	mult += 1000 * nr_iowait_cpu(smp_processor_id());
>  
>  	return mult;
>  }