Date: Wed, 09 May 2007 21:33:40 +0100 From: Rui Paulo <rpaulo@fnop.net> To: John Baldwin <jhb@freebsd.org> Cc: Attilio Rao <attilio@freebsd.org>, Perforce Change Reviews <perforce@freebsd.org>, Rui Paulo <rpaulo@freebsd.org> Subject: Re: PERFORCE change 119371 for review Message-ID: <86d519n3dn.wl%rpaulo@fnop.net> In-Reply-To: <86ejlpn3kq.wl%rpaulo@fnop.net> References: <200705062110.l46LAZqE011583@repoman.freebsd.org> <200705091457.39167.jhb@freebsd.org> <3bbf2fe10705091233t405121d2qda9a058ecf4124bc@mail.gmail.com> <200705091543.33002.jhb@freebsd.org> <86ejlpn3kq.wl%rpaulo@fnop.net>
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At Wed, 09 May 2007 21:29:25 +0100, Rui Paulo wrote: > > At Wed, 9 May 2007 15:43:32 -0400, > John Baldwin wrote: > > > > On Wednesday 09 May 2007 03:33:11 pm Attilio Rao wrote: > > > 2007/5/9, John Baldwin <jhb@freebsd.org>: > > > > On Sunday 06 May 2007 05:10:35 pm Rui Paulo wrote: > > > > > http://perforce.freebsd.org/chv.cgi?CH=119371 > > > > > > > > > > Change 119371 by rpaulo@rpaulo_epsilon on 2007/05/06 21:10:15 > > > > > > > > > > We don't need any scheduler support because: > > > > > 1) msrtemp is a child of cpu - this implies that every > > > > > rdmsr/cpuid instruction will be executed on that CPU. > > > > > > > > No, that isn't true. You do need to use sched_bind() for that so you are > > > > really on the desired CPU when you read the MSR. > > > > > > I think he just needs msr of the cpu where curthread is executed, so > > > any scheduler lock should be needed. > > > If he needs to know msr of a particular CPU he really needs so, but it > > > doesn't seem the case. > > > > The sysctl is per-CPU, so he needs the msr from a specific CPU in the sysctl > > handler. I.e., it's like dev.cpu.0.temp or some such. > > Yes, I need the MSR from a specific CPU. > Does sched_pin() solve the problem? Or do I need to use shed_bind()? Doh, forget this question.
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