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From: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
To: Arjan van de Ven <arjan@infradead.org>
Subject: Re: [PATCH 12/13] hrtimer: create a "timer_slack" field in the task struct
Cc: kosaki.motohiro@jp.fujitsu.com, linux-kernel@vger.kernel.org,
       torvalds@linux-foundation.org, dwmw2@infradead.org, drepper@redhat.com,
       mingo@elte.hu, tglx@tglx.de
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Date: Tue, 30 Sep 2008 14:16:09 +0900 (JST)
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Hi Arjan, 

Sorry for _really_ late responce.
I recently found this patch in linux-next.

In general, I like this patch.
However,

> +		case PR_SET_TIMERSLACK:
> +			if (arg2 <= 0)
> +				current->timer_slack_ns =
> +					current->default_timer_slack_ns;
> +			else
> +				current->timer_slack_ns = arg2;
> +			break;
>  		default:
>  			error = -EINVAL;
>  			break;

I wonder to why PR_SET_TIMERSLACK decreasing doesn't need root privilege.

example,
nice() systemcall is
  - nice increasing (pirority decreasing) doesn't need root privilege.
  - nice decreasing (priority incriasing) need root privilege.

So, I think time slack setting need similar one.
Otherwise, non-privilege user can increase power consumpsion easily by PR_SET_TIMERSLACK.

What do you think?