Date: Thu, 18 Aug 2005 07:31:24 -0700 From: Luigi Rizzo <rizzo@icir.org> To: Stephan Uphoff <ups@tree.com> Cc: arch@freebsd.org, Max Laier <max@love2party.net>, net@freebsd.org Subject: Re: duplicate read/write locks in net/pfil.c and netinet/ip_fw2.c Message-ID: <20050818073124.A87225@xorpc.icir.org> In-Reply-To: <1124374713.1360.64660.camel@palm>; from ups@tree.com on Thu, Aug 18, 2005 at 10:18:33AM -0400 References: <20050816170519.A74422@xorpc.icir.org> <200508170435.34688.max@love2party.net> <20050817170248.A70991@xorpc.icir.org> <200508180332.34895.max@love2party.net> <20050818005739.A83776@xorpc.icir.org> <1124374713.1360.64660.camel@palm>
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On Thu, Aug 18, 2005 at 10:18:33AM -0400, Stephan Uphoff wrote: > On Thu, 2005-08-18 at 03:57, Luigi Rizzo wrote: ... > > In fact i don't understand why you consider spinning and sleeping > > on a mutex two different things. > > The major difference between sleeping (cv_wait,msleep,..) and blocking > on a mutex is priority inheritance. > If you need to be able to use (non-spin) mutexes while holding a > [R|W]LOCK and use a [R|W]LOCK while holding a (non-spin) mutex then you > need to implement priority inheritance for [R|W]LOCKs. is that required (in FreeBSD, i mean) for algorithmic correctness or just for performance ? cheers luigi
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