From owner-freebsd-arch@FreeBSD.ORG  Thu Nov 23 07:09:16 2006
Return-Path: <owner-freebsd-arch@FreeBSD.ORG>
X-Original-To: freebsd-arch@freebsd.org
Delivered-To: freebsd-arch@freebsd.org
Received: from localhost.my.domain (localhost [127.0.0.1])
	by hub.freebsd.org (Postfix) with ESMTP id AEC1816A4C8;
	Thu, 23 Nov 2006 07:09:14 +0000 (UTC)
	(envelope-from davidxu@freebsd.org)
From: David Xu <davidxu@freebsd.org>
To: Bruce Evans <bde@zeta.org.au>
Date: Thu, 23 Nov 2006 15:09:08 +0800
User-Agent: KMail/1.8.2
References: <b1fa29170611220939g32469638ncf3a3ddd4bba3670@mail.gmail.com>
	<20061123170941.T36132@delplex.bde.org>
	<200611231453.34287.davidxu@freebsd.org>
In-Reply-To: <200611231453.34287.davidxu@freebsd.org>
MIME-Version: 1.0
Content-Type: text/plain;
  charset="iso-8859-1"
Content-Transfer-Encoding: 7bit
Content-Disposition: inline
Message-Id: <200611231509.08742.davidxu@freebsd.org>
Cc: arch@freebsd.org, Kip Macy <kip.macy@gmail.com>, Alan Cox <alc@cs.rice.edu>,
	freebsd-arch@freebsd.org
Subject: Re: superpage plans
X-BeenThere: freebsd-arch@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: Discussion related to FreeBSD architecture <freebsd-arch.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-arch>,
	<mailto:freebsd-arch-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-arch>
List-Post: <mailto:freebsd-arch@freebsd.org>
List-Help: <mailto:freebsd-arch-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-arch>,
	<mailto:freebsd-arch-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Thu, 23 Nov 2006 07:09:16 -0000

On Thursday 23 November 2006 14:53, David Xu wrote:
> Do you really believe IPI_PREEMPTION works as expected ? the problem
> is in sched_4bsd.c, the remote cpu running an idle cpu is only
> interrupted by IPI_AST not IPI_PREEMPT, IPI_AST has no effect for kernel
> thread, note that kick_other_cpu is only used for bound thread which is
> being resumed, kick_other_cpu does send IPI_PREEMPT,  though pagezero
> thread is a bound thread in most time, but it is not the case that
> kick_other_cpu will be used, we want to preempt it not resuem it, so
> PREEMPTION and IPI_PREEPMTION do not work for pagezero thread running
> on remote cpu.
>
> David Xu
the above may not be very clear.  The forward_wakeup only selects idle
cpu,  so a thread is being added will not preempt remote cpu which is
running pagezero thread.