Why do people say 8350 is a four core processor?

[twelve25]

Reading through the architecture for AMD Bulldozer and Piledriver processors, it is clear that each processor module has the hardware to handle 2 simultaneous threads on their own pipeline, except in the rare case of a 256 bit Floating point calculation where it has to share the two FPU units to perform the operation. Every other operation has a full path on it's own hardware through the CPU and 2 threads can pass without contention through each module.

As for sharing L2 cache, if you give each pair 2MB to share instead of 1MB of dedicated, there is no performance hit. L3 cache is shared at Intel, too.

It feels like everyone is missing these facts, but maybe its me. Why would someone say that AMD does not use "real" cores?

 

[jaguarskx]

I never heard of the FX-8350 being referred to as a 4 core CPU until this thread.

 

[Ajwork]

This sounds similar to what I heard about the FX-8150 when it first came out; while it was technically an eight core cpu, they were all actually part of two "monolithic" cores. AMD probably decided to put an additional mini core inside each core, probably with the hope of boosting performance (which it apparently did).

 

[stantheman123]

Because amd Cores arent like intels cores. That does not mean its not a real 8 core.

 

[Motopsychojdn]

I class them as quads as well,
quads with a wierd hyperthreading type function, but quads nonetheless
its been said before but when coding takes advantage of it, thats when you'll see BD and PD start to perform
Moto

 

[austenwhd]

People say that, mostly Intel fanboys, i am an regular Intel user and i say, it is actually 8 core CPU, best one in its price/performance range, you chose well. The force is strong with you.

 

[Motopsychojdn]

If that was at me Austen, I'm no Intel fan
Moto

 

[satyamdubey]

Even i think its better to call them Quad Modules with 2 cores in each module for smt.

 

[austenwhd]

If that was at me Austen, I'm no Intel fan
Moto

No, not at all, i was referring to people who usually support anything that Intel comes up with. Not you.

 

[rds1220]

I class them as quads as well,
quads with a wierd hyperthreading type function, but quads nonetheless
its been said before but when coding takes advantage of it, thats when you'll see BD and PD start to perform
Moto

I agree 100%.I would all it a quad core with something similar but not the same as hyperthreading.

 

[twelve25]

Do you guys know what Hyperthreading is? I throws two threads at one processor and if the processor has time to work on the extra thread while waiting for I/O or something, it executes the extra thread. Otherwise it gets kicked back and until the first thread finishes. It requires software support in the OS to work properly.

AMD has two distinct processors in each module that can work on two threads simultaneously. Yes there is only one Floating point scheduler, but it has two 128 bit FPU processing units so it can execute two Floating point operations at the same time, too.

 

[twelve25]

..... you chose well. The force is strong with you.

Me?

I have an overclocked i5 in my system, actually!

 

[abbadon_34]

As I see it
1) 4 modules each with 2 cores
2) Poor thread assignment in Win7 (updated, yet correct for Intel) overloads first module with 2 threads instead of moving thread to next module
3) total somewhere between 4 core hyperthreaded and true 8 core, leaning toward apps over games, as multithreaded apps are more likely to use max/unlimited threads over a specific numbers.
Shared L2 effect debatable

 

[Motopsychojdn]

No, not at all, i was referring to people who usually support anything that Intel comes up with. Not you.

No worries man
** It requires software support in the OS to work properly**
Kinda what I said no?

Moto

 

[austenwhd]

Me?

I have an overclocked i5 in my system, actually!

Well. if the other posters are to be believed, the force has only grown stronger with you.

 

[twelve25]

As I see it
1) 4 modules each with 2 cores
2) Poor thread assignment in Win7 (updated, yet correct for Intel) overloads first module with 2 threads instead of moving thread to next module
3) total somewhere between 4 core hyperthreaded and true 8 core, leaning toward apps over games, as multithreaded apps are more likely to use max/unlimited threads over a specific numbers.
Shared L2 effect debatable

4 modules x 2 cores = 8 cores?
The module can execute two threads simultaneously so this should not be an issue. Hyperthreading cannot execute two threads at the same time, period. It's not even close to the same.

 

[twelve25]

** It requires software support in the OS to work properly**

You said AMD would perform better with software support. It might, but not for the same reasons Hyperthreading needs software. Hyperthreading is, again, forcing two threads down one processor unit. Most of the time, this extra thread gets kicked back out and needs the OS to recognize that and work around it. AMD can actually process two threads at the same time, so no need for software support.

What could happen is that if Windows sent the first 1-4 threads each to a separate module, then those cores could have access to the full shared cache, and would likely perform a little bit better.

 

[abbadon_34]

See #2. Execution of two threads on a single module is not as effecient *usually* as two threads on two separate modules. AFAIK Windows assigns two separate threads to the same module with AMD vs. two threads two cores Intel, hyperthreading coming when the cores are used up.

I am by no means an expert and if I am wrong I am HAPPY to hear it, to justify an upgrade to a 8320 instead of i5-3770k

And I am using an AMD Phenom II.

 

[iam2thecrowe]

they have 8 integer cores. the problem with that is things like games dont use integer cores a lot. It has only 4 FPU's (floating point units) and that is what games use. so it has 8 full integer cores, but have to share 1 fpu between 2 cores.

 

[twelve25]

It has 4 FPU schedulers each with Two 128 bit FPU processing units (FMAC). It can run a total of 8 FPU threads, albeit with some possible overhead vs having 8 FPU schedulers.

 

[twelve25]

See #2. Execution of two threads on a single module is not as effecient *usually* as two threads on two separate modules. AFAIK Windows assigns two separate threads to the same module with AMD vs. two threads two cores Intel, hyperthreading coming when the cores are used up.
.

You are correct. I was looking for something to prove it, and this article seems to: http://techreport.com/review/21865/a-quick-look-at-bulldozer-thread-scheduling

If you use CPU masks to trick Windows into thinking it has only 1 core in each of 2 modules, you get 20% more performance vs it using two threads in one module. This means something is a bottleneck in the architecture, but I still have a hard time saying it isn't a dual core module. It's 2 cores in one module bottlenecked by some kind of architecture restraints.

 

[satyamdubey]

It throws two threads at one processor and if the processor has time to work on the extra thread while waiting for I/O or something, it executes the extra thread. Otherwise it gets kicked back and until the first thread finishes. It requires software support in the OS to work properly.

AMD has two distinct processors in each module that can work on two threads simultaneously. Yes there is only one Floating point scheduler, but it has two 128 bit FPU processing units so it can execute two Floating point operations at the same time, too.

true. thread for thread, AMD's smt through modules is nearly 4 times superior than HT. Thats simply because while HT can be hypothetically seen as a core woking at a max 20% efficiency, running two parallel threads, a BD module has one core at 100% and its sister core at 75-80%, with the performance hit coming from shared fpu scheduler and decoder.

 

[austenwhd]

they have 8 integer cores. the problem with that is things like games dont use integer cores a lot. It has only 4 FPU's (floating point units) and that is what games use. so it has 8 full integer cores, but have to share 1 fpu between 2 cores.

Ok, this is happening again, Intel and other companies advertise CPU(s) good or bad for gaming, trust me, i have discussed this before on other threads, they are not! A simple core 2 duo usually can get you through any extremely demanding games even these days with a efficient enough GPU, period. If you are buying a CPU (don't tell me for the iGPU, that is plainly stupid) for only playing games, buy a ivy i3 with any latest DX11 compatible Nvidia GTX , you are safe for next, atleast, 5 years.


IMO (this is first time i am using this!), most people, ie 99.99 % people buy a PC for all sorts of stuff, like browsing, chatting, downloading, watching blu ray rips (of pirate sites), doing video encoding (to upload on pirate sites) etc. etc. i won't care if i have a 8 core AMD or a similarly priced (or more) 4 core Intel, they are both efficient and capable for any or all of this at once. Before these multithreading days, modern computers were meant for multitasking, any 4 core (recent ones are always preferable) CPU these days is more than capable of doing that.

You don't buy High-end PC to play games, you buy a 8 Core, 4 Ghz+, 32 GB RAM, Z77 MB, GTX 670, configuration to do High-end HD video editing, 3D rendering etc. where nothing is good enough.

Multithreading is a term and technology introduced by Intel for Intel, doesn't make it industry standards.

 

[twelve25]

true. thread for thread, AMD's smt through modules is nearly 4 times superior than HT. Thats simply because while HT can be hypothetically seen as a core woking at a max 20% efficiency, running two parallel threads, a BD module has one core at 100% and its sister core at 75-80%, with the performance hit coming from shared fpu scheduler and decoder.

It would be insteresting to see if the "sister" core is running at 80% of the "main" core, or if they just both run at 90% when they have to share tasks. I mean, is there really a slower core out of each pair or do they just slow when sharing paths into the module and cache. If you could some how send a singe thread through and test core 1 and core 2 individually, that would give the answer, but I am not sure how to do it.

 

[twelve25]

Ok, this is happening again, Intel and other companies advertise CPU(s) good or bad for gaming, trust me, i have discussed this before on other threads, they are not! A simple core 2 duo usually can get you through any extremely demanding games even these days with a efficient enough GPU, period. If you are buying a CPU (don't tell me for the iGPU, that is plainly stupid) for only playing games, buy a ivy i3 with any latest DX11 compatible Nvidia GTX , you are safe for next, atleast, 5 years.



You don't buy High-end PC to play games, you buy a 8 Core, 4 Ghz+, 32 GB RAM, Z77 MB, GTX 670, configuration to do High-end HD video editing, 3D rendering etc. where nothing is good enough.

C'mon, man, you don't really believe this, do you? I'd venture to say 4/5 high end PC self-builds are for games by computer nerds like us. And as for an i3 or Core2Duo being enough to handle a high end Nvidia card, I'd only have to suppose you've never tried it. It is not! BF3 uses 85% of all four cores on my Sandy i5 during multiplayer. There are countless benchmarks showing slower and dual core processors as not being able to hit vsync on many titles.