Date: Tue, 26 Feb 2008 12:16:06 -1000 (HST) From: Jeff Roberson <jroberson@chesapeake.net> To: Daniel Eischen <deischen@freebsd.org> Cc: Brooks Davis <brooks@freebsd.org>, Andrew Gallatin <gallatin@cs.duke.edu>, Alfred Perlstein <alfred@freebsd.org>, arch@freebsd.org, Robert Watson <rwatson@freebsd.org>, David Xu <davidxu@freebsd.org> Subject: Re: cpuset and affinity implementation Message-ID: <20080226121251.V920@desktop> In-Reply-To: <Pine.GSO.4.64.0802261021560.8556@sea.ntplx.net> References: <20080220175532.Q920@desktop> <20080220213253.A920@desktop> <20080221092011.J52922@fledge.watson.org> <20080222121253.N920@desktop> <20080222231245.GA28788@lor.one-eyed-alien.net> <20080222134923.M920@desktop> <20080223194047.GB38485@lor.one-eyed-alien.net> <20080223111659.K920@desktop> <20080223213507.GD39699@lor.one-eyed-alien.net> <20080224001902.J920@desktop> <20080225231747.GT99258@elvis.mu.org> <20080225143222.B920@desktop> <Pine.GSO.4.64.0802252003060.3971@sea.ntplx.net> <20080225160433.P920@desktop> <Pine.GSO.4.64.0802252110280.3971@sea.ntplx.net> <20080225194320.V920@desktop> <Pine.GSO.4.64.0802260121160.6723@sea.ntplx.net> <20080225213434.L920@desktop> <Pine.GSO.4.64.0802261021560.8556@sea.ntplx.net>
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On Tue, 26 Feb 2008, Daniel Eischen wrote: > On Mon, 25 Feb 2008, Jeff Roberson wrote: > >> Binding a processor set to the process simply sets the per-thread binding >> of each thread in the process. There is otherwise no specific process >> binding. We could keep a pointer to the last specifically bound set in the >> process if we wanted, but what would it be used for other than querying the >> id of the process? What if each thread was seperately specifically bound >> to a different set? What set should be used on fork? The set of the >> process or the thread that called fork? What about when creating a new >> thread? > > The set used on fork should be the set of the calling thread, > same concept as signal masks I would think. Same thing when > creating a new thread. I guess I'd check how Linux and Solaris > do it, see if they are consistent. Yes, that's what I do now. The mask is inherited from the creater. I was just pointing out that it gets a little ambiguous if we were to have some notion of a per-process set. > > I can see how you might _not_ want to inherit bindings in a > created thread. For a process with real-time threads, the > application might start with superuser privileges, create some > threads with real-time priority and set their bindings, then > setuid() to remove superuser privileges. Is a privilege check > made in a newly created thread when applying inherited bindings? No privilege check on fork. This would create weird failure modes. > >> See above discussion. I'm not sure what you mean by 'default' cpuset here. > > I imagine the 'default' cpuset as the system's default cpuset, > in lieu of any administratively created cpusets and bindings > for the process (inherited or explicit). My opinion is that if we decide that it's important to assign numbered sets to tids we need then to allow cpuset_getid to return multiple ids for WHICH_PID. Jeff > > -- > DE >
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