Date: Tue, 28 Sep 2010 23:24:32 +0100 From: "Robert N. M. Watson" <rwatson@freebsd.org> To: sbruno@freebsd.org Cc: "freebsd-current@FreeBSD.org" <freebsd-current@freebsd.org>, Joshua Neal <jdneal@gmail.com> Subject: Re: MAXCPU preparations Message-ID: <A0A7B3BB-806C-40EA-B8FE-344EF0C8A187@freebsd.org> In-Reply-To: <1285699244.2454.63.camel@home-yahoo> References: <1285601161.7245.7.camel@home-yahoo> <alpine.BSF.2.00.1009280846490.69239@fledge.watson.org> <1285692311.2454.11.camel@home-yahoo> <201009281429.30747.jhb@freebsd.org> <1285699244.2454.63.camel@home-yahoo>
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On 28 Sep 2010, at 19:40, Sean Bruno wrote: >> If you go fully dynamic you should use mp_maxid + 1 rather than = maxcpus. >=20 > I assume that mp_maxid is the new kern.smp.maxcpus? Can you inject = some > history here so I can understand why one is "better" than the other? So, unlike maxcpus, mp_maxid is in theory susceptible to races in a = brave new world in which we support hotplug CPUs -- a brave new world = we're not yet ready for, however. If you do use mp_maxid, be aware you = need to add one to get the size of the array -- maxcpus is the number of = CPUs that can be used, whereas mp_maxid is the highest CPU ID (counting = from 0) that is used. Robert=
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