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Mac Forum / Country Specific / Australian Mac Group / November 2004G5 dual - when does second chip come in?
Hi i am steering my work towards getting some new G5's but don't know whether to try to get single or dual chips. When does the second chip cut in - only in programs that can use it? or is it running all the time when under load? Would it be better to go the fastest single or a dual 1.8? Thanks, Robotman. > When does the second chip cut in - only in programs that can use it? > or is it running all the time when under load? Operates all the time, the OS does a good job of splitting the load. However, only specially written programs will split *themselves* to work on both chips simultaneously. > Would it be better to go the fastest single or a dual 1.8? If you can afford it, the dual is a no-brainer decision here.  SignatureDavid J Richardson -- davidj@richardson.name http://davidj.richardson.name/ -- Dr Who articles/interviews/reviews http://www.boomerang.org.au/ -- Boomerang Association of Australia >>When does the second chip cut in - only in programs that can use it? >>or is it running all the time when under load? > > Operates all the time, the OS does a good job of splitting the load. > However, only specially written programs will split *themselves* to > work on both chips simultaneously. That's something to be wary of, if you buy a dual CPU machine, but then spend most of your time running a single-threaded app, one CPU could concievably sit mostly idle. It would at least allow the machine to stay response to other processes. >>Would it be better to go the fastest single or a dual 1.8? > > If you can afford it, the dual is a no-brainer decision here. > >>When does the second chip cut in - only in programs that can use it? > >>or is it running all the time when under load? [quoted text clipped - 7 lines] > concievably sit mostly idle. It would at least allow the machine to stay > response to other processes. If you have a one CPU machine, -that- CPU spends most of it's time idle as well. Even iTunes would keep a modern CPU busy only occasionally (a 400 Mhz G3 can play iTunes and a DVD at the same time without any problems). Dale Signaturedstanbro@spam.o.matic.bigpond.net.au > That's something to be wary of, if you buy a dual CPU machine, but then > spend most of your time running a single-threaded app, one CPU could > concievably sit mostly idle. It would at least allow the machine to stay > response to other processes. One of those other processes is the window server. It's long been known that dual CPUs are a win with such s/w architectures (where the display is handled by a separate process). Even when a single CPU is not loaded (as is mostly the case other than "extreme" compute situations as when doing a MPEG encode or rendering [and even that's getting offloaded to the graphics processor these days]) the extra CPU is a win as it typically less expensive to talk to the process on the other CPU than it is to switch between processes on a single CPU (e.g. cache doesn't get flogged and MMU state can be kept). The end result being the system feels a little more responsive. Go for two! |
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