Bring back high performance single core CPUs already!

[Frontino]

Yeah, I said it! I still don't get why they moved to many-core chips, when most applications (including modern games) requires algorithm dependencies and the best scale you can get is on a dual core, but that doesn't mean you won't get issues with that (lag, asynchronicity, sound effects muting..).
Just put on the market a 5 GHz single core CPU and let me buy that! Don't stick the many-core gimmick on everybody's mouth!

End of rant.

 

[hoho]

Would you like an integrated power plant with that CPU?

Also, the main bottleneck is memory latency. It's far harder to improve that than to improve CPUs to tolerate the high latency. Going multicore helps quite a bit with that in addition with tons of other benefits it brings.

 

[Alexko]

Who has moved to many-core CPUs? Most mainstream CPUs still have only 2 to 4 cores, and the high-end ones Turbo up to ~4GHz when only 1 or 2 are loaded.

 

[Lightman]

Nothing is black or white.
We are living in 'trade-off' world at the moment and multi-core is one of them.
Besides your 5GHz single core CPU will struggle really hard with many modern games, just to name BF3 among others.

 

[liolio]

Nothing is black or white.
We are living in 'trade-off' world at the moment and multi-core is one of them.
Besides your 5GHz single core CPU will struggle really hard with many modern games, just to name BF3 among others.

Indeed when I read the news, all too often by the way, there is indeed a lot of brown.
Brown seems to be the new grey... and there are a lot of shades of brown...

 

[french toast]

No thanks...give me a quad @3ghz over 1 at 5ghz....multi tasking would be a nightmare

 

[hoho]

multi tasking would be a nightmare

Yes, that's another point I forgot to mention earlier.

Moving from a single core to even a measily 2.8GHz Northwood P4 with HT was by far the biggest upgrade to system responsiveness I've seen. EVER. And that includes moving from 233MHz P1 with 16M RAM @ 40MB/s to 500MHz P3 with half a gig at some 5x+ higher throughput.

 

[hkultala]

Yeah, I said it! I still don't get why they moved to many-core chips, when most applications (including modern games) requires algorithm dependencies and the best scale you can get is on a dual core, but that doesn't mean you won't get issues with that (lag, asynchronicity, sound effects muting..).
Just put on the market a 5 GHz single core CPU and let me buy that! Don't stick the many-core gimmick on everybody's mouth!

End of rant.

The reason is simple:

We have reached the limits of what kind of performance is possible from..
1) single-core with current mfg technologies, AND
2) updating mfg technologies only give very small/slow increase in this.

Given current mfg technology:
1) much higher performance single cores are not possible.
2) slightly higher performance single cores require very high supply voltages leading to huge power consuption and cooling requirements.

If you try to make "bigger, fatter core" it will end up having worse clock speed, and the fatness only gives very small increase in ipc.
If you try to make processor with much longer clock speed, it will end up doing less per clock cycle


So, I'm expecting the performance in non-parallelizable tasks will only about double during next 10 years.

Performance with single thread with data parallel code may increase much more, when wider SIMD-instructions are introduced.

 

[Davros]

Many years ago there were rumours that the next amd cpu's would have "reverse hyperthreading"
where multiple cores would be used to run single threaded apps.

 

[swaaye]

I remember during the P4 and Athlon 64 days, when dual cores first showed up people were saying that we were at a dead end on x86 performance per clock per core. Maybe that was mainly the marketing push of the day (reviews like to regurgitate that stuff). Intel's vast army of brilliant minds continues to bring considerable improvements with even their tick/refresh CPUs. AMD seems to be heading backward though.

 

[hoho]

Many years ago there were rumours that the next amd cpu's would have "reverse hyperthreading"
where multiple cores would be used to run single threaded apps.

Yeah, I remember those and I still don't quite understand what kind of theory those rumors had behind themselves to even make it remotely useful and not require re-programming everything from scratch to be automatically parallelized and thus pretty much the same as using openmp on multicores today.

 

[imaxx]

you're thinking in a too GPU-centric way...

huge parallel work is a natural fit for GPUs, not so much on CPUs. Amdahl's law clearly states that the benefits of multithreading applies only to the parallel parts.
On CPU, it is not unlikely to find a 50% sequential work with the other 50% parallelizable.
so real benefits of multi-threading ends fast after 4-8 cores... whereas even a modest 5% increase in the single core speed would still yield a notable speedup.

It's easy (in a sense!) to cast parallel rays over a grid, not so easy to perform complex analysis with strong interactions, that's why single-core performances are still important.

 

[pcchen]

Single thread performance is still improving. For example, Sandy bridge is, clock for clock, faster than Nehalem. It's just that you don't really get much more from all the transistors if you focus on single thread performance. You may be able to make a single core CPU as large as a 8 core Sandy bridge, but its single thread performance is probably at most 50% faster and a 8 core Sandy bridge will kill it in most benchmarks (and real world applications too).

 

[Albuquerque]

and the best scale you can get is on a dual core, but that doesn't mean you won't get issues with that (lag, asynchronicity, sound effects muting..).

Not true. A multitude of games see scaling beyond dual core. And the 'threading' of an application is not linked to all the negatives that you outlined; a single-threaded app is more likely to have those issues than a multithreaded app simply because you could never truly be doing more than one thing at once.

... whereas even a modest 5% increase in the single core speed would still yield a notable speedup. <snip> that's why single-core performances are still important.

Nobody is ignoring IPC nor single-threaded performance. Newer architectures continue to deliver improvements to instructions-per-clock; and newer architectures also continue to deliver higher clocks to lesser-threaded tasks (see also: "turbo" technologies.) But there's only so much that can physically be done on that front.

 

[CarstenS]

I second the notion - partially.
I'd really love to have high-IPC, high-clocked Few-Core-CPU. Personally, I still haven't seen the dire need to upgrade to a quadcore from my C2D E8500 with a little OC. I might have jumped on the i3-train, if they'd been better overclockable or maybe if Intel had offered a "k"-model.

Most of the programs I use on a regular basis, don't need high performance at all. Some that do, do not make use of more cores, but rather enjoy high IPCs or high clocks (image manipulation with GIMP for example) or single-player RPGs like Dragon Age an it's successor.

So, if they're clocked high enough or if they are overclockable, I really would consider going for an Ivy Bridge dualcore (with Hyperthreading possibly, just in case), instead of a quadcore where I'm paying for many more transistors I rarely use.

Many years ago there were rumours that the next amd cpu's would have "reverse hyperthreading"
where multiple cores would be used to run single threaded apps.

And that's exactly what you get when someone drops you a hint about an upcoming technology and you're trying to spin a story from it. Bulldozer's modules are in a way the opposite of Hyperthreading, joining ressources of different cores to work on a joint taks (AVX) - if you want to view it that way. Same thing with Fermi having "not one tessellator" - you could spin it in a way, that Fermi does not have a tessellator (with the emphasis on "a" being lost) and come to the conclusion it does everything in software, therefore must be painfully slow.

 

[suryad]

I think it would be silly to go back to a single core no matter how high the IPC might be. As it is we can alreayd see Intel is improving not only the electrical and thermal efficiency of the processors but it's IPC and number of cores as well which I think is the right way to go. I went from a quad core to a hexacore and the only apps I noticed the biggest improvement was in Java development and games as well. I have not overclocked my cpu and I have played the same games before on a quad core and on the hexa core so my conclusion is that IPC helped in that department. But when I am running a git pull, and a maven build, and firing up multiple instances of Intellij, and opening up sql developer to run some sql queries, etc etc, ther performance improvement has been drastic...which I attribute to the number of cores as well as the IPC improvements. Now all I really need to maxmixe performance is an SSD and that time is coming near as it seems one of my velociraptors is starting to fail.

 

[imaxx]

Nobody is ignoring IPC nor single-threaded performance. [...] But there's only so much that can physically be done on that front.

Check out the 50% line at 8 core. Assuming more than 50% parallelism (unless you're doing raytracing or similar stuff) within a single application is not trivial.
Clearly, it's ok for specific segments (multiple background applications, web-services etc.) with higher parallelism.
It is also interesting to see the 95%/2048 cores curve.

 

[Albuquerque]

I don't see how your reply has anything to do with mine.

Total instructions computed per clock continues to increase, however there is a hard physical limit as to how 'fast' a single core will be able to perfom. Your chart has nothing to do with the physical limit I'm talking about.

You can point to "ZOMG SINGLE CORE PERFORMANCE MATTERS" and I've said nothing to counter that, because it's true. But that has no bearing on the physical limits of our world and the manufacturing capabilities we have at our disposal. Sorry, you will have to find another way to 'express' that work, or else simply accept that work is not going to get markedly faster in the forseeable future.

 

[Sxotty]

If we are making random complaints why cant I get a cheap 8 core chip? I went from a 6 core AMD to a 4 core Intel since intel decided 6 core chips must be exorbitantly expensive, but I miss my 6 cores.

 

[I.S.T.]

Most of the programs I use on a regular basis, don't need high performance at all. Some that do, do not make use of more cores, but rather enjoy high IPCs or high clocks (image manipulation with GIMP for example) or single-player RPGs like Dragon Age an it's successor.

Dragon Age 1 actually likes 3 core minimum CPUs a lot more than dual cores...