This is in regards to the older PPC Macs. Simple inquiry as to how Logic makes use of dual processors. -Does it always split the load evenly? -Do 3rd party plugins (both DSP and AUi) use both processors. -Does the OS, or Logic have the final say how the load is distributed. (I'm thinking the OS) -What's the obvious benefit of dual processors used with Logic. Well, not the most obvious but the most noticeable difference between a single and a dual. Howard

> This is in regards to the older PPC Macs. Darn, my computer's getting old.. :o) > -Does it always split the load evenly? It starts every new thread (see below) on the processor with the least load. Since threads will cause different loads, the load will never be spread completely evenly, but it's trying. :o) > -Do 3rd party plugins (both DSP and AUi) use > both processors. They can, but don't always. As mentioned, any separate thread (a single undevidable process) can be put on its own on a CPU. Most plugins are single threads, so any of those plugins can themselves only occupy one CPU. Some heavier plugins are multithreaded themselves and can be devided over the CPUs even when there is only one of those plugins active in total. > -Does the OS, or Logic have the final say how the load > is distributed. (I'm thinking the OS) Logic is responsible for starting threads, but it's _probably_ the OS that determines what CPU the thread is ran on. That's just my educated guess though. :o) > -What's the obvious benefit of dual processors > used with Logic. Well, not the most obvious but the > most noticeable difference between a single and a dual. Well, almost twice the power. :o) Especially with a large number of plugins (meaning lots of raw calculation power required), a dual 1.8GHz simply means 1.8GHz extra processing power compared to a single 1.8. The DISadvantage compared to a single proc twice as fast (if it would exist) :o) is that you don't always have the full double power; mainly because both procs have to communicate through the same bus, and you can't always devide the threads to make 100% use of both procs. Hope this info is useful :o) Maurits.

--- In logic-users@yahoogroups.com, Maurits van de Kamp wrote: Maurits, Thanks, this does help, couple more comments. >>This is in regards to the older PPC Macs. > >Darn, my computer's getting old.. :o) I know, in looking for information online most articles were about Intel Macs. >>-Does it always split the load evenly? > >It starts every new thread (see below) on the processor with the >least load. Since threads will cause different loads, the load will >never be spread completely evenly, but it's trying. :o) Ok, got it. >> -Do 3rd party plugins (both DSP and AUi) use >> both processors. > >They can, but don't always. As mentioned, any separate thread (a >single undevidable process) can be put on its own on a CPU. Most >plugins are single threads, so any of those plugins can themselves >only occupy one CPU. Some heavier plugins are multithreaded >themselves and can be devided over the CPUs even when there is only >one of those plugins active in total. This raises the question, do plugins that are single threaded necessarily focus on only one of the CPU's. Does the OS sees one of the CPUs as #1(main), the other as #2(secondary). If so, single threaded plugins _may_ only load one processor. Or, do new single threaded processes open on the least used processor? Sorry for all the questions, just trying to firm up my understanding of Logic's dual CPU use. > >>-What's the obvious benefit of dual processors >> used with Logic. Well, not the most obvious but the >> most noticeable difference between a single and a dual. > >Well, almost twice the power. :o) Ok, that's the obvious one. :-) >Especially with a large number of >plugins (meaning lots of raw calculation power required), a dual >1.8GHz simply means 1.8GHz extra processing power compared to a >single 1.8. The DISadvantage compared to a single proc twice as >fast (if it would exist) :o) is that you don't always have the full >double power; mainly because both procs have to communicate through >the same bus, I've heard it's approx an 80% increase in processing power. -Does using the same bus ever cause bus saturation when using intense EFX plugins like reverb. Or when using PCI solutions like UAD-1? -Does a single processor machine get along better with hardware DSP (like UAD)? -Do dual processor systems ever introduce audio artifacts under load (because of the inter communication) that single processor systems I'm done, no more questions. >Hope this info is useful :o) Very much so.

>>> This is in regards to the older PPC Macs. >> >> Darn, my computer's getting old.. :o) > > I know, in looking for information online most articles > were about Intel Macs. Well it's true of course, PPC is the previous generation. I was just being melancholic. :o) > Or, do new single threaded processes open on the least used processor? Yes, by "one processor" I meant one at a time, not a specific one. :o) Both procs are equally important, the thing is just that a single thread cannot be devided. > I've heard it's approx an 80% increase in processing power. Yes, sounds plausible. > -Does using the same bus ever cause bus saturation when using > intense EFX plugins like reverb. Or when using PCI solutions > like UAD-1? Theoretically it could I guess, but I never heard of this happening. In fact, what's intense about those plugins is the amount of calculation power required (which happens inside the CPU), not so much the data passed on between the processors and/or the audio interface. > -Does a single processor machine get along better with > hardware DSP (like UAD)? No idea, I never heard of any problems but I don't use that kind of hardware myself. > -Do dual processor systems ever introduce audio artifacts under load > (because of the inter communication) that single processor systems No, for two reasons: First, threads are programmed to run independantly (whether on one or more processors) so the communication between the threads is taken care of (unless there's a bug). :o) Second, the way digital audio calculations work, if the communication (or indeed the processing itself) gets in trouble for lack of power, the whole thing just gives up like it normally does in case of a CPU overload. (Well there is the option to switch off overload messages, I guess then there will just be a bit of silence in the audio). But there won't be any "slight" deviations in the signal because of this (in the sense that audio quality might degrade with almost overloaded processors), I think that's what you were after. Oh and for what it's worth, I'm very happy with my dual 1.8GHz performance. They gladly take on their share of Garritan Personal Orchestras, Space Designers and Guitar Amp Pros. :o) > I'm done, no more questions. I don't mind the questions. :o) Maurits.

--- In logic-users@yahoogroups.com, Maurits van de Kamp wrote: >>Or, do new single threaded processes open on the least used >>processor? > >Yes, by "one processor" I meant one at a time, not a specific >one. :o) Both procs are equally important, the thing is just that a >single thread cannot be devided. Right, understood, that's what I thought. >>-Do dual processor systems ever introduce audio artifacts under load >>(because of the inter communication) that single processor systems > >No, for two reasons: First, threads are programmed to run >independantly (whether on one or more processors) so the >communication between the threads is taken care of (unless >there's a bug). :o) Second, the way digital audio calculations >work, if the communication (or indeed the processing itself) >gets in trouble for lack of power, the whole thing just gives up >like it normally does in case of a CPU overload. > >Oh and for what it's worth, I'm very happy with my dual 1.8GHz >performance. They gladly take on their share of Garritan Personal >Orchestras, Space Designers and Guitar Amp Pros. :o) > >>I'm done, no more questions. > >I don't mind the questions. :o) Thanks for taking the time to answer, big help. Howard

Maurits van de Kamp <maurits@bassment.nu> wrote: > Oh and for what it's worth, I'm very happy with my dual 1.8GHz > performance. They gladly take on their share of Garritan Personal > Orchestras, Space Designers and Guitar Amp Pros. :o) Hi! Just curious, G4 or G5? Thanks! -scott

>> Oh and for what it's worth, I'm very happy with my dual 1.8GHz >> performance. They gladly take on their share of Garritan Personal >> Orchestras, Space Designers and Guitar Amp Pros. :o) > > Hi! Just curious, G4 or G5? Thanks! G5, sorry I forgot to mention that :o) Maurits.