From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from sc8-sf-mx1-b.sourceforge.net ([10.3.1.11] helo=sc8-sf-mx1.sourceforge.net) by sc8-sf-list1.sourceforge.net with esmtp (Exim 4.30) id 1BRqG5-0004EO-Kq for user-mode-linux-devel@lists.sourceforge.net; Sun, 23 May 2004 03:31:09 -0700 Received: from smtp004.mail.ukl.yahoo.com ([217.12.11.35]) by sc8-sf-mx1.sourceforge.net with smtp (Exim 4.30) id 1BRqG4-00007m-Uq for user-mode-linux-devel@lists.sourceforge.net; Sun, 23 May 2004 03:31:09 -0700 From: BlaisorBlade Subject: Re: [uml-devel] preemption References: <20040518134726.36369.qmail@web14002.mail.yahoo.com> <20040518183838.GA29175@ccure.user-mode-linux.org> In-Reply-To: <20040518183838.GA29175@ccure.user-mode-linux.org> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Disposition: inline Message-Id: <200405231118.44464.blaisorblade_spam@yahoo.it> Sender: user-mode-linux-devel-admin@lists.sourceforge.net Errors-To: user-mode-linux-devel-admin@lists.sourceforge.net List-Unsubscribe: , List-Id: The user-mode Linux development list List-Post: List-Help: List-Subscribe: , List-Archive: Date: Sun, 23 May 2004 11:18:44 +0200 Content-Transfer-Encoding: quoted-printable To: user-mode-linux-devel@lists.sourceforge.net Alle 20:38, marted=EC 18 maggio 2004, Jeff Dike ha scritto: > On Tue, May 18, 2004 at 06:47:26AM -0700, Sam King wrote: > > >From what I can tell, when the guest kernel takes a > > > > timer interrupt (SIGALRM) it eventually updates the > > tsk->need_resched parameter for processes that have > > been running for too long. However, I do not see > > where the actual switch takes place except in the > > interrupt_end() function which is only called as a > > result of guest application system calls and signals. > > Exactly. Every kernel entrance is either a system call or signal (a UML > signal, not a process signal, BTW), so there is a preemption opportunity > at every return to userspace. But when you say "UML signal" (I guess a signal between the host UML thread= s)=20 you mean even a timer interrupt, right? Otherwise I don't see how a=20 non-syscalling process (a true CPU-hog, like SETI@home or such things) coul= d=20 be interrupted. --=20 Paolo Giarrusso, aka Blaisorblade Linux registered user n. 292729 ------------------------------------------------------- This SF.Net email is sponsored by: Oracle 10g Get certified on the hottest thing ever to hit the market... Oracle 10g.=20 Take an Oracle 10g class now, and we'll give you the exam FREE. http://ads.osdn.com/?ad_id149&alloc_id=8166&op=CCk _______________________________________________ User-mode-linux-devel mailing list User-mode-linux-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel