CPU recomendation Duo or Quad?

[BFisher]

Q6600 here - and it's worked fabulous. I have 2 HD OTA tuners, and 2 SD tuners for set top boxes; and 5 Extenders. 90% of what I record is HD so lots of transcoding going on, and commercial skipping.

I pushed it best I could - putting 3 HD shows (transcoded) on extenders, and a DVD on another extender, while recording 2 HD shows (required 2 commercial skips to be running) and it was around 40% utilization. I can't imagine needing much more processor than that...

[davephan]

One thing to keep in mind about sustained CPU load with Windows operating systems is that Windows cannot function effectively if the sustained CPU load becomes too high. I heard several years ago that Windows operating systems cannot handle much more than 42% sustained CPU load before the system performance drastically drops.

To contrast CPU load. On mainframes, the CPU load can run continueously at 98 or 99 percent without any problems.

I also found that my memory consumption had a similar effect. It seems that you need to allow for CPU and memory 'headroom' with Windows operating systems. If either sustained CPU or memory consumption become too high, the Windows system performance crumbles.


Dave

[sandor]

Originally Posted by davephan

One thing to keep in mind about sustained CPU load with Windows operating systems is that Windows cannot function effectively if the sustained CPU load becomes too high. I heard several years ago that Windows operating systems cannot handle much more than 42% sustained CPU load before the system performance drastically drops.

To contrast CPU load. On mainframes, the CPU load can run continueously at 98 or 99 percent without any problems.

I also found that my memory consumption had a similar effect. It seems that you need to allow for CPU and memory 'headroom' with Windows operating systems. If either sustained CPU or memory consumption become too high, the Windows system performance crumbles.


Dave

if you heard this several years ago, most likely it wouldn't apply now. windows, like most every other modern OS has gotten much more multi-threaded ability over the past 5 years. and windows (compared to the macintosh OS 9) has always been much better at dealing with multi-threads. any mac os 9 users remember photoshop or toast completely locked down the OS until the operations were done?)

and ram, well, most modern OS'es will use up as much ram as possible for caching disk activity (on my macs i almost never have "free" ram in OS X, but it is not necessarily actively being used.)

back with windows 98 and Me, i could see your thoughts being accurate, but in years of using NT 2000 and XP, nah - as long as you have a properly powered CPU and enough RAM for your tasks.

[reggie14]

I think there's some truth to his claim, but its mostly a scheduler issue. I don't think the Windows NT/XP scheduler properly gives interactive processes priority over non-interactive ones. If I convert videos on my main desktop, a dual core machine, it makes the machine pretty unresponsive. But, if I drop the priority of that process to the lowest setting, I barely notice its even going.

Also, dual core seemed to help a lot. Even with the priority change, on my single core machines converting video causes a pretty noticeable slowdown. I suppose having 2 cores to schedule to allows the interactive processes twice the chance to execute.

Windows XP doesn't prefetch stuff like Vista does, and I wasn't aware OS X did either. So, I often have a gig or more memory free on my XP machine. I've noticed a pretty big slowdown when I get close to using my 2 gigs of RAM.

[sandor]

Originally Posted by reggie14

I think there's some truth to his claim, but its mostly a scheduler issue. I don't think the Windows NT/XP scheduler properly gives interactive processes priority over non-interactive ones. If I convert videos on my main desktop, a dual core machine, it makes the machine pretty unresponsive. But, if I drop the priority of that process to the lowest setting, I barely notice its even going.

Also, dual core seemed to help a lot. Even with the priority change, on my single core machines converting video causes a pretty noticeable slowdown. I suppose having 2 cores to schedule to allows the interactive processes twice the chance to execute.

Windows XP doesn't prefetch stuff like Vista does, and I wasn't aware OS X did either. So, I often have a gig or more memory free on my XP machine. I've noticed a pretty big slowdown when I get close to using my 2 gigs of RAM.

XP was the first Windows OS to prefetch, 80286's were the first Wintel processors to prefetch. In the Apple world, prebinding is basically the same thing, prebinding has been around since 10.1 (now at 10.5)

there have definitely been marked improvements in both OS'es in terms of multi-threads, but to base assumptions on data more than a year or two old in the technology sector is a bit dangerous. (which was/is my whole point)

[reggie14]

The Windows XP prefetching is completely different than the Vista prefetching. My understanding is that XP prefetch waits until you open a program, then it loads stuff that it thinks that program will need. Vista, on the other hand, will try to load data that it thinks you'll use sometime in the future, even before you run programs that might need it. So, while Vista will try to use a significant portion of your available memory, XP will not.

Instruction prefetch is a different beast where the processor gets instructions from memory before it actually needs it. This isn't relevant to the discussion of prefetching programs/data into main memory.

I'm not a Mac guy, but I think Mac OS X prebinding is like Windows XP prefetch, and won't actively try to eat up as much memory as it can.

I think you're exaggerating how quickly things change. Its usually pretty safe to use data several years old, depending on the level of abstraction you're concerned with. Windows 2000/XP was mostly static for about 7 years, and really I bet its pretty close to NT4. I don't think the Mac kernel has changed that much, particularly when compared to the Mach kernel which has been around a while. You said there had been major changes to multitasking in the last 5 years, but I don't see any. I know Vista has a new scheduler which tries to prioritize certain things like video playback heavily (and allegedly causes some problems too), but I can't imagine its really that much different.

edit: But, if all you're intending to say is that Windows XP and Mac OS X have improved multitasking over Windows 9x and Mac OS9, then I agree. But, in general, I don't agree with your statement that modern OSes eat up as much RAM as they can through prefetching (except for Vista, and maybe OS X).

[sandor]

Originally Posted by reggie14

The Windows XP prefetching is completely different than the Vista prefetching. My understanding is that XP prefetch waits until you open a program, then it loads stuff that it thinks that program will need. Vista, on the other hand, will try to load data that it thinks you'll use sometime in the future, even before you run programs that might need it. So, while Vista will try to use a significant portion of your available memory, XP will not.

makes sense.

I'm not a Mac guy, but I think Mac OS X prebinding is like Windows XP prefetch, and won't actively try to eat up as much memory as it can.

os x prebinding allows certain tasks and API's (correct term??) that are used by multiple applications to be stored once in RAM and then used by a multitude of apps. so certain interface and system tasks and such can have one instance in RAM, yet be accessed by any app that needs it, instead of each app having to load a new instance of that same item.

I think you're exaggerating how quickly things change. Its usually pretty safe to use data several years old, depending on the level of abstraction you're concerned with. Windows 2000/XP was mostly static for about 7 years, and really I bet its pretty close to NT4. I don't think the Mac kernel has changed that much, particularly when compared to the Mach kernel which has been around a while. You said there had been major changes to multitasking in the last 5 years, but I don't see any. I know Vista has a new scheduler which tries to prioritize certain things like video playback heavily (and allegedly causes some problems too), but I can't imagine its really that much different.

yes, windows development seems asininely slow. but on the os x side, every 18 months since 10.0 there has been a dramatic update to the OS - while there have been some "pretty" upgrades, there have been many more dramatic changes to the underpinnings of the OS - better handling of threads, multi-threaded finder, a true mulit-threaded finder in 10.5, etc. in fact, the base of the OS is where the most dramatic operation changes have occurred in os x, and most of it in the past five years...

edit: But, if all you're intending to say is that Windows XP and Mac OS X have improved multitasking over Windows 9x and Mac OS9, then I agree. But, in general, I don't agree with your statement that modern OSes eat up as much RAM as they can through prefetching (except for Vista, and maybe OS X).

[/quote]

os x for sure will "use" all the ram available, especially the longer i run the OS. it simply keeps information in RAM tagged "inactive", which allows it to be instantly used for a new task, or if you return to the process that is still in RAM, it can pick up right where it left off.



a proper multi-threaded OS shouldn't show dramatic slow downs under heavy CPU use, and to say that once you hit 42% CPU utilization you have peaked is quite a claim to make on baseless hearsay from a couple years ago.

thats my main point...