Intel Dual Core Performance Preview Part II: A Deeper Look
by Anand Lal Shimpi on April 6, 2005 12:23 PM EST- Posted in
- CPUs
Final Words
The point of this article was to present you with the choice that you'll be making, should you decide to upgrade to a new system in the coming months; the choice between very fast single task performance (and to some extent, light multitasking performance) or more responsive, heavy multitasking performance. No one is really exempt from this decision and you'll have to come to the decision based on your own needs.
We've shown the Athlon 64 to have extremely solid single threaded performance. With the exception of our encoding tests, the Athlon 64 really can't be beat when it comes to running a single application.
The tables are turned as soon as multitasking is introduced, where you can't beat the fact that the Pentium D is able to fulfill the needs of more applications running in the background.
So, the question quickly becomes, how heavy of a multitasker are you? If you're primarily a gamer and you find your gaming performance gets bogged down at all by the tasks you're running in the background, then dual core will most likely outweigh the benefits of a strong single core CPU. If not, then your answer is clear: go for the faster single core.
For encoding performance, you still can't beat the Pentium D. Even a dual core Athlon 64 isn't going to help enough in that area.
To characterize all other non-gaming, non-encoding performance is extremely difficult. For the most part, if you're doing a lot of things at the same time or if you have a lot of applications eating up CPU time - you're better off with the Pentium D. If you are a much cleaner operator and don't have all that much going on, then a single core CPU will still be your best bet; and what better single core to have than the Athlon 64.
The surprise here is the impact of NCQ on multitasking performance. The difference in two of our tests was not only measurable, but also quite noticeable in real world usage. Given that NCQ is quickly becoming a "free" feature of new hard drives, it's a feature that we'd strongly recommend to have in your next system. It doesn't improve performance across the board, but it doesn't hurt things and when it does work, it works extremely well.
With all this excitement, we still have to keep ourselves grounded in the thought that dual core isn't here yet; it's still as much as two months away. For AMD, as we've known all along, the wait is going to be a bit longer on the desktop. The workstation and server markets will be serviced by AMD first, and we will have a look at workstation/server dual core performance as soon as AMD launches those parts. It's looking like, at least on the desktop, if you want dual core at a reasonable price point, your only option will be Intel. But the prospect of more affordable dual core chips out of AMD in 2006 is quite exciting as well.
A dual core Athlon 64 solves a lot of our dilemmas simply because you get stronger single threaded performance than the Pentium D (in everything but encoding) while also getting the multitasking benefits of dual core.
For Intel, the Pentium D is a saving grace - it's the first time that we've been interested in any processor based on the Prescott core. It's also perfect timing; if it weren't for the Pentium D, we'd have no interest in the Intel 945 and 955 chipsets, and definitely not in NVIDIA's new nForce4 SLI Intel Edition product. With that said, it should be pretty clear what our next article in this series will be...
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saratoga - Friday, April 8, 2005 - link
#90:HT is the same thing as SMT. You can thank Intel's marketing for that one.
Reflex - Friday, April 8, 2005 - link
#93: Intel has labeled it as SMT, however there is another name for what they are doing(that I cannot remember at the moment). What they are calling SMT is nowhere even close to solutions like Power.That aside, the implementation Intel has chosen is designed to make up for inefficiencies in the Prescott pipeline, such a implementation would make zero sense on the Athlon architecture, it does not share the same inefficiencies that the P4 design has. It would actually harm rather than help performance.
True SMT is not a 'bolt on' feature. Its something that has to be planned for from the very beginning of the CPU design cycle. You could not in any way add it to the current Athlon design and gain any performance. Whatever their next generation is may include it, it depends on what direction they decide to go, but you will not see it on the current generation, and thats actually a good thing as it would be purely a marketing move.
eeceret - Friday, April 8, 2005 - link
As always a very interesting article, one thing comes to mind though... In the gaming multitasking tests you adjusted the priority of the DVD Shrink process to see the effect on gaming performance. What I was wondering is if you could take a look at what effect explicitly binding the processes to seperate cores (processor affinity) has on gaming performancedefter - Friday, April 8, 2005 - link
Hyperthreading IS SMT. SMT stands for symmetric multithreading (ability to run two or more threads at once and this is exactly what hyperthreading does.Of course, CPUs from different manufacturers have vastly different internal structures, thus also the SMT is implemented differently.
"Intel's next major IA-32 processor release, codenamed Prescott, will include a feature called simultaneous multithreading (SMT)"
http://arstechnica.com/articles/paedia/cpu/hyperth...
tynopik - Friday, April 8, 2005 - link
and of course that's just the net part, don't want to leave out other background tasks like that resource sucker outlook and playing flac/ape filestynopik - Thursday, April 7, 2005 - link
to get repeatable multi-tasking/ncq benches, anand is going to have to bite the bullet and setup a full-blown network simulation:1: an nntp server
2. a bittorrent swarm
3. an irc server
with this setup, you can test these multi-tasking scenarios that seem more reasonable:
1. firewall (a pig like zonealarm)
2. pulling news articles with either 2 clients or 1 client with 2 threads (writing to different places on hd simultaneously)
3. about 10 torrents where it is BOTH downloading and uploading (so pulling from a gazillion different places on hd at once)
4. mirc with about 5 open channels and some scripts (like filters). At least one channel should be very high traffic (like #mp3passion on undernet)
5. icq
6. running all this with software raid 5
this would represent a typical background load, and then you can benchmark foreground tasks to see how much they are affected by what's going on in the background (specifically ncq could be tested by seeing how long it takes to copy a file from one partition to another under these circumstances)
Reflex - Thursday, April 7, 2005 - link
Just to be clear: SMT is NOT the same thing as HyperThreading. They go about what they are doing in radically different ways. The only similarity is in the CPU being able to execute two simultanious threads. How it goes about that though is implemented completely differently.Reflex - Thursday, April 7, 2005 - link
"#47, if HT is simply a "bandaid", then why is AMD the only major CPU vendor not using it? IBM uses it heavily in their Power5, Sun is making their next CPUs (Niagra) very highly SMT (same thing as HT). Arguably, both of those architectures have much more shallow pipelines than the P4, yet see reason to provide SMT. AMD is the only holdout."The SMT used in IBM's Power series is completely different from what Intel is doing with the P4 design. The only similarity is the fact that two threads can be run at once, the implementation has nothing even close to the same however. I do not have details on Sun's implementation, but I would assume it will be closer to IBM's than Intel's implementation considering the market they are targetting. The Power architecture was designed from the ground up to use SMT, it wasn't a tacked on feature, and you get considerably more of a performance boost in most scenerios with it than you would ever see with HT on Intel.
The Athlon64 architecture was not designed with SMT or HT in mind, it was designed around two physical cores. So adding HT to it would do very little, and SSE3(which mostly optimizes HT style multithreading) does almost nothing on the K8 architecture.
Not every feature would help every CPU design, it all depends on what was taken into account when the design was made. Power has some limitations you do not see on x86(in order execution for example), and x86 has challenges you do not see on Power. The multi-threading implementations are similarly different and not comparable. In the x86 world, HT makes sense on Intel in some situations(not always). It makes no sense on AMD and would likely result in performance drops rather than gains. It certainly would not improve performance in any way as the core does not often have idle units or execution steps due to its design.
Icehawk - Thursday, April 7, 2005 - link
"I'm also curious to see what effects RAID would have on testing striped setups."Uh, delete the "striped setups" from the end ;)
Can we please, please get some kind of short-term editing abilities here?
Icehawk - Thursday, April 7, 2005 - link
So you'd rather wait for information than recieve it now?Anand clearly shows that dual core is only a good choice now IF you use it in scenarios where it can run multiple applications. Otherwise, single core chips are still the better choice. So i don't see the marketing hype you are referring to. Basically we've been told now for quite a few years that multi-taskers can benefit from multiple CPUs but the costs have been prohibitive. Now it looks like within the next year a 2 CPU machine will cost no more than previous single core processors.
Thanks Anand for helping us out in planning for the future! The DVDShrink stuff was very interesting to me as was the NCQ information - makes switching to SATA drives a bit more appealing to me considering my usage profile.
I just recently went from 1.4 k7->3.2 P4 w/HT so I'm pretty happy at this point. It does look like a dual core system *might* allow me to get rid of my second box (the 1.4 K7) which would save me money in the long run - one less PC to power up and cool off. My home office requires year round A/C to cool my 2 21" CRTs and 2 PCs...
I'm also curious to see what effects RAID would have on testing striped setups. I'm very curious if a RAID5 type of setup with NCQ and a dual-core might make chores like encoding & gaming realistic - it sounds like from the review that at this point I/O may cause hiccups even when the processor still has headroom.