From: Jeff Dike <jdike@addtoit.com>
To: Sam King <sam_king18@yahoo.com>
Cc: user-mode-linux-devel@lists.sourceforge.net
Subject: Re: [uml-devel] preemption
Date: Tue, 18 May 2004 14:38:38 -0400 [thread overview]
Message-ID: <20040518183838.GA29175@ccure.user-mode-linux.org> (raw)
In-Reply-To: <20040518134726.36369.qmail@web14002.mail.yahoo.com>
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.
Jeff
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next prev parent reply other threads:[~2004-05-18 17:52 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-05-18 13:47 [uml-devel] preemption Sam King
2004-05-18 18:38 ` Jeff Dike [this message]
2004-05-23 9:18 ` BlaisorBlade
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