Date: Sun, 20 Dec 1998 22:28:20 +0000 (GMT) From: Karl Pielorz <kpielorz@tdx.co.uk> To: Alfred Perlstein <bright@hotjobs.com> Cc: hackers@FreeBSD.ORG Subject: Re: question about re-entrancy. Message-ID: <Pine.BSF.4.05.9812202222270.27500-100000@caladan.tdx.co.uk> In-Reply-To: <Pine.BSF.4.05.9812201621560.6331-100000@bright.fx.genx.net>
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On Sun, 20 Dec 1998, Alfred Perlstein wrote: > > I'm a bit confused. I've been watching the discussions going on about > SMP. The issue of kernel re-entrancy has been brought up many times. > > So here's the question: > > I thought the kernel was re-entrant, when a process makes a syscall it's > thread of execution enters the kernel where its arguments are validated > and careful checks are done to ensure security then the syscall is done. Hmmm... AFAIK the FreeBSD kernel at the moment is like the Linux one certainly used to be (at last week ;-) - i.e. under SMP the kernel has a big lock around it - so that only 1 CPU can actively be in the kernel at a time... I beleive it's also the goal to make the granularity on this 'big lock' ever finer as more code get's developed... > Or are the spl calls simply there to diable interupts? but that brings me > back to the question about "well how do nfsd and nfsiod do it?" Hmmm... At the risk of being totally wrong - I thought that's all they did?... > Mike, Terry, Matt, John? Uhgh, yes - good idea, I'll leave it for someone who knows what their talking about to give the 'right' answer :-) - Some of the details for the current SMP implementaion were hanging around on www.freebsd.org a while ago... -Kp To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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