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CPU - Cache vs. Clockspeed

C

Cheesepie

Member
In different applications, which applications (games, video editing, etc) utilize the cache more and which one utilizes higher clockspeeds? Are both important for games?
 
High clock speed is obviously a big factor in any application, no?

From gaming benchmarks I've seen over the past years I can't recall one that responded to cache size. I guess most decent CPU's these days have enough cache (for games).

Back in the day like 10-15 years ago things were different with some cache-starved CPU's.
 
It depends on the working set size. But overall clockspeed wins if you compare across currently released models.

For example on Core 2. It was only a few % from 2MB or 4MB cache. Easily beaten by 133Mhz faster clock. Only photoshop gave a 10% increase.
 
Ahhh, this reminds me of an old story...

Back in the Cel 300A days Intel sold a 300MHz Celeron with 128KB of fast on die cache for cheap and they also sold the Pentium 2 with 512KB of slower off die cache.

At stock speeds the Cel with 128KB of fast cache was as fast or faster than the P2 with 512KB of slower cache. The Cel 300A was cheaper and faster and easy to massively overclock so it destroyed the P2 in every way, this in spite of the P2 having 4x the cache.

Read some history if you are curious:

http://www.anandtech.com/show/174

I'm guessing that the situation with cache is just like system RAM, if you have enough, more is not going to help much at all. If don't have enough, more will make a big difference.
 
I agree. But everyone was saying that a 566MHz Coppermine Celeron overclocked to 850Mhz was about as fast as a Pentium III 733MHz.
 
On my past and few remaining AMD machines, cache size has made a significant difference in gaming performance.
 
Cache matters in games more than some would have you believe. Don't have time to go digging for links, but I remember seeing benchmarks on xbitlabs back when they were reviewing the Intel C2D vs the AMD K8. The e2100 series with the small cache was not only piss poor compared to the similar Intel cpu with more cache, but even lackluster compared to the K8.

With modern cpu's having an IMC, cache size seems to matter less these days. Then there's also the question of cache speed. Faster cache is one of the advantages Intel currently has over AMD.
 
From Anandtech back in 2006.

L2cachecomparison.png


Core 2 Duo E6300 (1.86GHz/2MB) to a hypothetical 1.86GHz Core 2 Duo with a 4MB L2 cache.
Click to expand...
 
Cheesepie said:
In different applications, which applications (games, video editing, etc) utilize the cache more and which one utilizes higher clockspeeds? Are both important for games?
Click to expand...
CPUs with small caches tended to fall behind much more than equally-clocked CPUs with much more, after they are a few years old. Also, Intel was known to reduce cache performance in the process of reducing size, which was one of the reasons many older Intel CPUs faltered with larger data sets. Chopping the cache in half was bad, but chopping it in half (or even quarter!) by reducing the ways is what made it bad enough to spend more money on a better CPU 🙂. As that got to be less of an issue, they made sure the memory interface was crippled (C2D era).

AMD was different, but not mucn, in practice. A Sempron at the same speed as an A64, FI, was close to the performance, but a few years down the road, feels sluggish like a Celeron, while the A64s hang in there.

With the needs of games and content creation applications, today (in that a truly crippled cache subsystem on an otherwise fast CPU would be stupid to bother doing, compared to other options, as too many things would be too slow without enough), I think we have reached a point where most CPUs have enough cache to feed them, so it's not really a concern, outside of servers.

IoW, your i5-2500 might need that extra 3MB to feed two more real cores...but it has it. Meanwhile, the i3-2320 is sharing time between only two cores, so when it could use more cache, it could probably also use more real cores. By having the smaller-cache CPU also have fewer cores and lower clock speeds, it will tend to balance out.
 
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lakedude said:
Ahhh, this reminds me of an old story...

Back in the Cel 300A days Intel sold a 300MHz Celeron with 128KB of fast on die cache for cheap and they also sold the Pentium 2 with 512KB of slower off die cache.

At stock speeds the Cel with 128KB of fast cache was as fast or faster than the P2 with 512KB of slower cache. The Cel 300A was cheaper and faster and easy to massively overclock so it destroyed the P2 in every way, this in spite of the P2 having 4x the cache.
Click to expand...
Not true. At equal clock speeds (CelA 300 @ 450, P-II 300 SL2W8 @ 450), the PII had better multi-tasking "smoothness", due to the much larger cache.

This is why I purchased a PII-300 SL2W8 (guaranteed 450Mhz) chip, rather than cheaped out on the CeleronA. Not everyone just plays games. Some of us compile/run code too.
 
VirtualLarry said:
Not true. At equal clock speeds (CelA 300 @ 450, P-II 300 SL2W8 @ 450), the PII had better multi-tasking "smoothness", due to the much larger cache.

This is why I purchased a PII-300 SL2W8 (guaranteed 450Mhz) chip, rather than cheaped out on the CeleronA. Not everyone just plays games. Some of us compile/run code too.
Click to expand...
Ahh I see you are correct. The Cel was not better at everything after all. Sorry my mistake.

Cheesepie did mention games twice in the OP so gaming was clearly one of the things to be concerned with.

Sometimes people get tunnel vision when it comes to usage. For many people the Cel 300A was just perfect because it was fast (for gaming, and other single threaded apps I presume), and it was cheap. Clearly you knew what you were doing when you bought the P2 with multitasking in mind. Back then I avoided multi-tasking, in fact I avoided multitasking for years until XP and multi core CPUs came about. Multi-tasking on 98 or Me was a bit sketchy as I recall...
 
lakedude said:
Ahhh, this reminds me of an old story...

Back in the Cel 300A days Intel sold a 300MHz Celeron with 128KB of fast on die cache for cheap and they also sold the Pentium 2 with 512KB of slower off die cache.

At stock speeds the Cel with 128KB of fast cache was as fast or faster than the P2 with 512KB of slower cache. The Cel 300A was cheaper and faster and easy to massively overclock so it destroyed the P2 in every way, this in spite of the P2 having 4x the cache.

Read some history if you are curious:

http://www.anandtech.com/show/174

I'm guessing that the situation with cache is just like system RAM, if you have enough, more is not going to help much at all. If don't have enough, more will make a big difference.
Click to expand...

I have to postjack this .. awsome times AND cpu .. had a 300a that did 504mhz and blew right past any flagship offered at the moment .. holy crap.. and had a friend that did the hardhack with actually drilling holes in the celerons to enable dual mode ... dual 300@450's baby ... back in the day.
Damn im old.
 
You actually don't want the core clock speed to be too fast because that means the cache will have to have higher latency or a lower clock speed. I'm guessing if both the cores and all cache on BD had ran at 2.6GHz (and a 400 MHz boost with half of the cores disabled) then the cache would've been able to have significantly less latency, and that it may not have been anywhere near as slow in practice. I could very well be wrong about that though.
 
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