Single Core, Dual Core, Quad Core?

I have been noticing STILL some folks making false comments about processors based upon their number of cores.

I wanted to share some info/good reads about multi-core environments.

Hopefully some folks will take away a better understanding of the single vs dual vs quad core processors and how they affect performance and why.

Things discussed are memory usage, OS utilization/scheduling, IO, threading and multiple processes/multitasking even when you are not multitasking .

The Dr Dobbs article about coding for a shared cache is very very interesting as it defines what "could" be an advantage of the C2D over the K10 (although recent docs have stated that maybe a smaller shared cache will be used with the K10 too). This advantage is only recognized if the code is correct in its usage of the shared cache (see the table in the article).

Understand these reads are mostly from a developer standpoint but they give a very good basis for both SMP and Multi-Core.

So here goes:

http://www.ddj.com/dept/64bit/196902836
http://www.realworldtech.com/page.cfm?ArticleID=RWT121106171654&p=1
http://www.intel.com/cd/ids/develo [...] htm?page=2
http://www.devx.com/go-parallel/Article/27399

New Links 06/05/07:
IBM SMP information
Micro Kernel Link with the BEST "quick" description of OS operations I have seen!!

This is true...

However using processor/core affinity would correct that issue would it not?

If you are on Core 0 and use affinity to keep ya there, you would be doing just fine as that core ONLY has access to that L2 cache segment.

Thing is if you were to code an app with affinity enabled (through OS) if it were to later PORT to a truely native quad core with shared L2 between all cores it would NOT require any changes to code.

This gets back to fully understanding the hardware of the system you are on.

Very true...

Makes me wonder how most OSes would treat the Core 2 Quad core affinity. Will the OS see it as a generic quad core CPU or more correctly as 2 seperate dual core CPUs?

Would not be a far fetched Idea!

Given their dual core HT enabled Extreme Processors of the past I would not see this far from the truth at all.

Ranman,

Also, remember that Intel may offer an Intel specific library that may ensure affinity is correct. Limiting parent and child processes to the same core grouping would not be that difficult.

Psuedo Code

if (get_core(Parent))
{
push.child(get_core(Parent));
}

Also,

This white paper covers it pretty well too.

Intel HT White Paper

Here is your answer:

That makes the most sense to ensure the highest performance is maintained.

Thanks for the help on that ches111 and JumpingJack!

Jack I think we would all have to agree that,

If Intel threw HT into the Dual Core or even the Quad Core 8O mix?

and

Developers create multithreaded applications (DUH!).

The combination would in fact be a very difficult to beat system. K8L would even have to go back to the drawing board.

HT was somewhat ineffective because of the previous coding practices and somewhat meager support from the OS.

HT could be a boon for the up and coming generation of software!

Croc,

Leveki must be living in different times than I.

I have and will continue to use compilers that allow for threads to be used.

There is even a thread standardization that been available in nearly ALL environments for ages.

You pick up ANY C++ and now Java compiler and you can easily write multi-treaded applications.

Even if you do not use multithreaded applications you still gain by using the multi-core environment.

The next time you get that program not responding error remember you could have been on a multi-core box

Some updated info just for fun...

Cakewalk benchys... That show up to a 60% increase one over the other.

Dual Core E6600 vs Quad Core X6700

Bumpage!!

They are sometimes a pain in the rear... I understand... ...
Maybe we can write a more comprehensive review, and include some of the frequently asked questions (E6850 vs. Q6600 for instance), and ask turpit to put it as sticky.

I just don't like how people just barge into a forum, put on capslock, and start typing their questions, without doing a little search around. If you need help, we'll help you. But that doesn't mean you come in here unprepared.