Date: Tue, 20 Dec 2005 14:22:35 -0500 From: John Baldwin <jhb@freebsd.org> To: freebsd-current@freebsd.org Cc: Luigi Rizzo <rizzo@icir.org>, Julian Elischer <julian@elischer.org>, current@freebsd.org Subject: Re: td->td_critnest manipulations do not use atomic_add_int ? Message-ID: <200512201422.47323.jhb@freebsd.org> In-Reply-To: <43A855A5.6070809@elischer.org> References: <20051220032538.A33093@xorpc.icir.org> <43A855A5.6070809@elischer.org>
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On Tuesday 20 December 2005 02:04 pm, Julian Elischer wrote: > Luigi Rizzo wrote: > >as in the subject... i see that td->td_critnest (used to determine > >whether a thread can be preempted or not) is manipulated using > >plain ++ or -- instruction instead of the atomic_add_int(). > > > >I wonder if declaring it as volatile and possibly its > >usage patterns are enough to make the two things equivalent > >on all architectures. > > is td ever != curthread? No. -- John Baldwin <jhb@FreeBSD.org> <>< http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve" = http://www.FreeBSD.org
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