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From: Jesse Barnes <jbarnes@virtuousgeek.org>
To: vatsa@in.ibm.com
Cc: Tony Lindgren <tony@atomide.com>,
	Lee Revell <rlrevell@joe-job.com>,
	Nick Piggin <nickpiggin@yahoo.com.au>,
	schwidefsky@de.ibm.com, jdike@addtoit.com,
	Ingo Molnar <mingo@elte.hu>,
	linux-kernel@vger.kernel.org, george@mvista.com
Subject: Re: [RFC] (How to) Let idle CPUs sleep
Date: Thu, 12 May 2005 10:59:59 -0700	[thread overview]
Message-ID: <4283999F.8080609@virtuousgeek.org> (raw)
In-Reply-To: <20050512171251.GA21656@in.ibm.com>

Srivatsa Vaddagiri wrote:

>Even if we were to go for this tickless design, the fundamental question
>remains: who wakes up the (sleeping) idle CPU upon a imbalance? Does some other
>(busy) CPU wake it up (which makes the implementation complex) or the idle CPU 
>checks imbalance itself at periodic intervals (which restricts the amount of
>time a idle CPU may sleep).
>  
>
Waking it up at fork or exec time might be doable, and having a busy CPU 
wake up other CPUs wouldn't add too much complexity, would it?

>I guess George's experience in implementing tickless systems is that
>it is more of an overhead for a general purpose OS like Linux. George?
>  
>
The latest patches seem to do tick skipping rather than wholesale 
ticklessness.  Admittedly, the latter is a more invasive change, but one 
that may end up being simpler in the long run.  But maybe George did a 
design like that in the past and rejected it?

Jesse

  reply	other threads:[~2005-05-12 18:00 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-05-07 18:27 Srivatsa Vaddagiri
2005-05-08  3:50 ` Rusty Russell
2005-05-08  4:14   ` Nick Piggin
2005-05-08 12:19     ` Srivatsa Vaddagiri
2005-05-09  6:27       ` Nick Piggin
2005-05-12  8:38         ` Srivatsa Vaddagiri
2005-05-11 18:03     ` Tony Lindgren
2005-05-12  8:46       ` Srivatsa Vaddagiri
2005-05-12 16:01         ` Lee Revell
2005-05-12 16:16           ` Tony Lindgren
2005-05-12 16:28             ` Jesse Barnes
2005-05-12 17:12               ` Srivatsa Vaddagiri
2005-05-12 17:59                 ` Jesse Barnes [this message]
2005-05-12 18:16                   ` Tony Lindgren
2005-05-13  6:27                   ` Srivatsa Vaddagiri
2005-05-12 18:08                 ` Martin Schwidefsky
2005-05-12 18:21                   ` Tony Lindgren
2005-05-13  6:23                   ` Srivatsa Vaddagiri
2005-05-13  7:16                     ` Nick Piggin
2005-05-13  8:04                       ` Ingo Molnar
2005-05-13  8:27                         ` Nick Piggin
2005-05-13  9:19                           ` Srivatsa Vaddagiri
2005-05-13  9:33                             ` Nick Piggin
2005-05-12 21:16                 ` George Anzinger
2005-05-12 21:35                   ` Jesse Barnes
2005-05-12 22:15                     ` George Anzinger
2005-05-13  0:43                       ` Jesse Barnes
2005-05-13  6:31                         ` Srivatsa Vaddagiri
2005-06-30 12:47     ` Srivatsa Vaddagiri
2005-07-06 17:31       ` Srivatsa Vaddagiri
2005-05-08 10:13   ` Arjan van de Ven
2005-05-08 13:33     ` Andi Kleen
2005-05-08 13:44       ` Arjan van de Ven
2005-05-08 14:53         ` Andi Kleen
2005-05-08 13:31 ` Andi Kleen
2005-05-08 15:26   ` Srivatsa Vaddagiri

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