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CPU for multitasking

post #1 of 34
1/28/05 at 9:18pm
Thread Starter 
I often do multi-tasking on my laptop, ie having a video rendering in the background, or encoding MP3s, while still using Office applications in the foreground.

And I notice sluggisgness in my 1.7 Dothan.

I have a chance to get a very good price of a 2.0 Dothan A190, or for about the same price I could get a p4 3.4 or an Athlon 64 3400 or 3700.

So which, in a multitasking environment as described, would perform best?
Gaming is not important here.

Cheers

Steve
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post #2 of 34
1/28/05 at 9:37pm
Amd64 !!!!!!!!!!!!!
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post #3 of 34
1/28/05 at 10:21pm
Thread Starter 
Sorry, I guess I should have phrased my question a little more carefully.

Does anyone have objective benchmarks or hands on experience in a multitasking environment?
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post #4 of 34
1/29/05 at 2:21am
there have been a few reviews of multitasking. The p4 comes out on top in that respect. In regards to multitasking and video/audio encoding, the p4 is still better.

http://www.extremetech.com/article2/...1478694,00.asp
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post #5 of 34
1/29/05 at 10:12pm
Thread Starter 
That, and some others I've seen, seem fairly convincing for the P4 over the AMD. I wonder how a Dothan goes.

Steve
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post #6 of 34
1/29/05 at 10:17pm
Quote:
Originally Posted by sfdoddsy
That, and some others I've seen, seem fairly convincing for the P4 over the AMD. I wonder how a Dothan goes.

Steve
For multitasking, Dothan is not as good as AMD64/ P4. Test result shows.
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post #7 of 34
1/29/05 at 11:26pm
Hardly. While the Dothan is a great chip (I'm typing this on a Dothan 1.7), it's not as good as a P4 at multitasking.

The P4s have hyperthreading, which gives it superior multitasking ability. Even if it's not faster with hyperthreading than other processors overall, a P4 in HT mode can run two threads simultaneously instead of resorting to pre-emptive multitasking on the operating system level. Because of this, interrupts can occure on both threads simultaneously; the system will operate much smoother. Keep in mind smoother is not the same as faster. It may not be faster, it will simply be more responsive under heavy multitasking.
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post #8 of 34
1/30/05 at 3:41am
Quote:
Originally Posted by Guspaz
Hardly. While the Dothan is a great chip (I'm typing this on a Dothan 1.7), it's not as good as a P4 at multitasking.

The P4s have hyperthreading, which gives it superior multitasking ability. Even if it's not faster with hyperthreading than other processors overall, a P4 in HT mode can run two threads simultaneously instead of resorting to pre-emptive multitasking on the operating system level. Because of this, interrupts can occure on both threads simultaneously; the system will operate much smoother. Keep in mind smoother is not the same as faster. It may not be faster, it will simply be more responsive under heavy multitasking.
Exactly. In this respect, P4's have the advantage because of the Hyperthreading. AMD 64 does not have a clear advantage on multitasking.
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post #9 of 34
1/30/05 at 3:47am
dothans will be worse than amd 64 in multitasking. remember, the amd 64 has really fast access to memory with very low latencies.
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post #10 of 34
1/30/05 at 6:16am
I wish the P4's had more memory. Having the core share resources with two threads hurt's its performance. You’re talking about a chip that was originally designed to process a single thread. Then you have it process two threads with the same amount of resources.

Also, the P4 will run hotter, which could result in throttling. It won't be any good if you are multi-tasking and all of a sudden the P4 decides to slow down because it is getting hot. There goes your performance edge.

Too bad we didn't have Cell available for Laptops! (16 Cores!)
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post #11 of 34
1/30/05 at 8:54am
Thread Starter 
Well, there's only one way to find out for sure, and I'll make money out of it either way thanks to the joys of over-priced laptops in Australlia.

I'm on a trip to the States and have nabbed a 2.0 Dothan (A190) and a 3.06HT P4 (GRT360ZG), both Sony Xbrites.

Once I get them home I'll do some testing and see what happens.

Cheers

Steve
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post #12 of 34
1/30/05 at 3:10pm
Steve,

I would love to see a comparison between those two setups, particularly how much of a speed difference there is rendering the same file. Should be interesting to see how well the Dothan does against a P4 with HT. I'll be looking out for your posts.
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post #13 of 34
1/30/05 at 8:14pm
That's the thing. I'm saying that a processor's ability to multitask has nothing to do with performance, it has to do with responsiveness.

ChaosBlizzard: There is (usually) no performance HIT from running hyperthreading. You forget that even on non-HT processors, they still have to run multiple threads, just not at the same time. Threads are still competing for cache space and registers. Only they get swapped in and out repeatedly.

That said, the entire idea behind hyperthreading is that one single thread is rarely able to fully use all the processor's resources. The intention of HT is that two threads can use the existing resources more fully than one thread. This is where HT's 5 to 10 percent speed boost comes from. However on top of that you are truely running two threads simultaneously, which leads to greater responsiveness; for one thing each thread can have interrupts happening on it, so if one thread is trying to use up the entire CPU, the OS threads on the second virtual CPU can still receive interrupts.
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post #14 of 34
1/30/05 at 10:32pm
A processors ability to multi-task does have to do with performance. What do you think responsiveness falls under?

Why do you think Sony, IBM, Toshiba and others are developing a 16 core Cell processor? So things can respond faster? You do realize that processor is over 100x's faster than a P4 (Performance). This is simple because it can handle 16 threads at once.

What do you mean still receive interrupts? Regardless of what a processor is doing, if it receives an interrupt, it must stop. This is how it works on any pre-emptive system.

One thread can't use a single core's resources huh? Go out and buy a normal P4, and see if you can't hit 100% utilization. I bet you will be able to, and seeming how that is a single thread I guess that means it can utilize the chips resources quite well.

I run two P3's at 1.0GHz apeace. They don't just respond faster, they ARE faster.
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post #15 of 34
1/30/05 at 11:44pm
Just because a CPU is at 100% utilization doesn't mean it's resources are being fully utilized. Is the cache empty or full? Is the branch predicter mispredicting? Is the pipeline full? Etc.

Anyhow I was referring more to software interrupts. If one thread is totally monopolizing the CPU, and the OS tries to send a message to an app that a mouse click has occured in it's window, it might not receive it until the OS can get the first thread off the CPU. If there is a slot open for a second thread (HT), it can do it without needing to wait for the first thread to be pre-empted. At least, this is my understanding of it. And my observations have backed by observations of how one runaway thread can totally hose system responsiveness if you let it.
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post #16 of 34
1/31/05 at 1:23am
If it's using 100% of its processing power the cache is full. You tell me otherwise and you need to go back to the books.

Runway thread and pre-emptive don't belong in the same sentence with each other. When was the last time you seen a "run-away" thread in a pre-emptive system? Besides, today’s systems use 2, 3 or sometimes even more ways to schedule a thread and run a process.

You do realize Windows 2000 is both a co-operative system, pre-emptive system, and a priority scheduling system?
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post #17 of 34
1/31/05 at 1:28am
Quote:
Originally Posted by sfdoddsy
I often do multi-tasking on my laptop, ie having a video rendering in the background, or encoding MP3s, while still using Office applications in the foreground.

And I notice sluggisgness in my 1.7 Dothan.

I have a chance to get a very good price of a 2.0 Dothan A190, or for about the same price I could get a p4 3.4 or an Athlon 64 3400 or 3700.

So which, in a multitasking environment as described, would perform best?
Gaming is not important here.

Cheers

Steve
the A64 3700 will definitely do the best, not because of the CPU core alone, but more because of the Hypertransport at 1600MHz duplex, and the lower memory latency by the on die controllers, which are both important in multitasking. And 3700 will be about 15-20% faster than a 2.0 GHz Dothan, but neither in honesty, will blow anyone away in multitasking. If you are a serious multitasker, the best thing is not to get an LT, but to get a dual Xeon or Opteron to supplement the abilities of your LT.
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post #18 of 34
1/31/05 at 1:32am
If you want to multi-task the best bet is to actually have two processors. I am using a dual P3 system right now, and it was well worth the money.

I don't know of any dual processor Laptops though.

Does the original poster need it to be a Laptop?
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post #19 of 34
1/31/05 at 1:42am
Quote:
Originally Posted by ChaosBlizzard

I don't know of any dual processor Laptops though.
I know Sun Microsystems make dual CPU laptop servers, but they cost >>5000 and weight almost 20 pounds. At that point, desktop looks better and better as a solution.
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post #20 of 34
1/31/05 at 1:43am
For that kind of money you can build a great dual Xeon system. I spent $3300.00+ on my dual P3 system. It has other things, like RAID and what not though.

Or he can wait until dual core CPUs come out.
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