Date: Wed, 19 Mar 2008 11:42:44 -0700 From: Jeremy Chadwick <koitsu@freebsd.org> To: Chuck Robey <chuckr@chuckr.org> Cc: FreeBSD-Hackers <freebsd-hackers@freebsd.org> Subject: Re: remote operation or admin Message-ID: <20080319184244.GA29838@eos.sc1.parodius.com> In-Reply-To: <47E1558A.2030107@chuckr.org> References: <47DF1045.6050202@chuckr.org> <20080318082816.GA74218@eos.sc1.parodius.com> <47E146F9.5060105@chuckr.org> <20080319172213.GA28075@eos.sc1.parodius.com> <47E1558A.2030107@chuckr.org>
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On Wed, Mar 19, 2008 at 02:03:54PM -0400, Chuck Robey wrote: > Well, I am, and I'm not, if you could answer me one quiestion, then I would > probably know for sure. What is the difference between our SMP and the > general idea of clustering, as typified by Beowulf? I was under the > impression I was talking about seeing the possibility of moving the two > closer together, but maybe I'm confused in the meanings? SMP as an implementation is mainly intended for single systems with multiple processors (e.g. multiple physical CPUs, or multiple cores; same thing). It distributes kernel operations (kernel threads) across those processors, rather than only utilising a single processor. Clustering allows for the distribution of a task (a compile using gcc, running of certain disk I/O tasks, running multiple userland (or I suppose kernel, if the kernel had clustering support) threads) across multiple physical computers on a local network. The best example I have for real-world clustering is rendering (mostly 3D, but you can "render" anything; I'm referring to 3D in this case). A person doing modelling creates a model scene using 3D objects, applies textures to it, lighting, raytracing aspects, vertex/bones animation, and anything else -- all using their single workstation. Then the person wants to see what it all looks like -- either as a still frame (JPEG/PNG/TIFF), or as a rendered animation (AVI/MPG/MJPEG). Without any form of clustering, the workstation has to do all of the processing/rendering work by its lonesome self. This can take a very, very long time -- modellers aren't going to wait 2 hours for their work to render, only to find they messed up some bones vertexes half way into the animation. With clustering, the workstation has the capability to send the rendering request out onto the network to a series of what're called "slaves" (other computers set up to handle such requests). The workstation says "I want this rendered. I want all of you to do it". Let's say there's 200 machines in the cluster as slaves, and let's say all 200 of those machines are dual-core (so 400 CPUs total). You then have 400 CPUs rendering your animation, versus just 2 on the workstation. The same concept can apply to compiling (gcc saying "I want this C file compiled" or whatever), or any other "distributed computing" computational desired. It all depends on if the software you want to support clustering can do it. Different clustering softwares run at different levels; some might act as "virtual environments", thus underlying software may not need to know about clustering (e.g. it "just works"); others might require each program to be fully cluster-aware. Make sense? :-) -- | Jeremy Chadwick jdc at parodius.com | | Parodius Networking http://www.parodius.com/ | | UNIX Systems Administrator Mountain View, CA, USA | | Making life hard for others since 1977. PGP: 4BD6C0CB |
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