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From: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
To: Arjan van de Ven <arjan@infradead.org>
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
Subject: Re: [PATCH 12/13] hrtimer: create a "timer_slack" field in the task struct
Date: Tue, 30 Sep 2008 17:54:34 +0900 (JST)	[thread overview]
Message-ID: <20080930173528.6132.KOSAKI.MOTOHIRO@jp.fujitsu.com> (raw)
In-Reply-To: <20080930012839.1bb8c2e1@infradead.org>

Hi Arjan,

Thank you for quick responce.

> > 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?
> 
> setting timerslack to 0 has no real negative effects on the system on
> the one hand, on the other hand, it'll be multimedia apps and games who
> want to do this.
> 
> Requiring this type of app to be root doesn't sound like a good idea,
> especially since all you get by "cheating" is ... the exact behavior
> you ask for anyway. "Increased power consumption" isn't a root
> privilege, the app can consume much more power just by a "while (1);"
> loop for example.

Right.

But I worry about an end user can't find a application which 
spent large power comsumption.
Many laptop users think battery life is really really important.

end user can find "while(1)" app easily by top command.
but they can't find timerslack==0 app easily.

So, I can drop my proposal. but I hope you explain your expected end user usages.




  reply	other threads:[~2008-09-30  8:54 UTC|newest]

Thread overview: 46+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-09-01 23:03 [PATCH 0/13] Turn hrtimers into a range capable timer Arjan van de Ven
2008-09-01 23:05 ` [PATCH 1/13] hrtimer: add abstraction functions for accessing the "expires" member Arjan van de Ven
2008-09-01 23:05 ` [PATCH 2/13] hrtimer: convert kvm to the new hrtimer apis Arjan van de Ven
2008-09-01 23:06 ` [PATCH 3/13] hrtimer: convert timerfd " Arjan van de Ven
2008-09-01 23:07 ` [PATCH 4/13] hrtimer: convert net::sched_cbq " Arjan van de Ven
2008-09-01 23:08 ` [PATCH 5/13] hrtimer: convert kernel/* " Arjan van de Ven
2008-09-01 23:09 ` [PATCH 6/13] hrtimer: convert powerpc/oprofile " Arjan van de Ven
2008-09-01 23:09 ` [PATCH 7/13] hrtimer: convert kvm-ia64 " Arjan van de Ven
2008-09-01 23:10 ` [PATCH 8/13] hrtimer: convert s390 " Arjan van de Ven
2008-09-01 23:11 ` [PATCH 9/13] hrtimer: convert sound/ " Arjan van de Ven
2008-09-01 23:12 ` [PATCH 10/13] hrtimer: rename the "expires" struct member to avoid accidental usage Arjan van de Ven
2008-09-01 23:12 ` Arjan van de Ven
2008-09-01 23:13 ` [PATCH 11/13] hrtimer: turn hrtimers into range timers Arjan van de Ven
2008-09-02  8:22   ` Peter Zijlstra
2008-09-02 11:08     ` Peter Zijlstra
2008-09-02 11:15       ` Peter Zijlstra
2008-09-02 13:06       ` Arjan van de Ven
2008-09-02 13:05     ` Arjan van de Ven
2008-09-02 13:47       ` Peter Zijlstra
2008-09-02 16:02         ` Arjan van de Ven
2008-09-01 23:14 ` [PATCH 12/13] hrtimer: create a "timer_slack" field in the task struct Arjan van de Ven
2008-09-02 10:04   ` Pavel Machek
2008-09-02 13:03     ` Arjan van de Ven
2008-09-08 13:27       ` Pavel Machek
2008-09-08 13:40         ` Arjan van de Ven
2008-09-08 14:15           ` Pavel Machek
2008-09-08 14:22             ` Arjan van de Ven
2008-09-13 16:24               ` Pavel Machek
2008-09-14 15:21             ` Ulrich Drepper
2008-09-14 15:27               ` Arjan van de Ven
2008-09-14 15:57               ` Pavel Machek
2008-09-14 16:04                 ` Ulrich Drepper
2008-09-14 16:14                   ` Arjan van de Ven
2008-09-17  7:42                   ` Pavel Machek
2008-09-30  5:16   ` KOSAKI Motohiro
2008-09-30  8:28     ` Arjan van de Ven
2008-09-30  8:54       ` KOSAKI Motohiro [this message]
2008-09-01 23:14 ` [PATCH 13/13] hrtimer: make select() and poll() use the hrtimer range feature Arjan van de Ven
2008-09-02  8:22   ` Peter Zijlstra
2008-09-02 16:03     ` Arjan van de Ven
2008-09-06 14:56 ` [PATCH 0/13] Turn hrtimers into a range capable timer Ingo Molnar
2008-09-06 16:30   ` Arjan van de Ven
2008-09-06 16:33     ` Ingo Molnar
2008-09-12  3:39 ` Rusty Russell
2008-09-12  5:42   ` Arjan van de Ven
2008-09-12 20:24   ` Thomas Gleixner

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