couple of questions concerning multi core cpu's

This is a discussion on couple of questions concerning multi core cpu's within the Tech Board forums, part of the Community Boards category; hello all, i have some questions concerning multi core processors which i couldnt find the exact answer for them , ...

  1. #1
    بابلی ریکا Masterx's Avatar
    Join Date
    Nov 2007
    Location
    Somewhere nearby,Who Cares?
    Posts
    493

    couple of questions concerning multi core cpu's

    hello all, i have some questions concerning multi core processors which i couldnt find the exact answer for them ,
    i would appreciate it if any of you guys answer my questions or direct me to find my answers .
    ok .
    how is the architecture of a typical multi core cpu ? i mean suppose we have a quad core cpu,
    does this cpu have 4 ALU ? 4 CU ? inside itself ?(do we have these stuff for each core? )
    or no there is only one ALU and one CU for all of the cores ?
    in multi core cpu's , are each core a complete standalone cpu or not? its just lets say a part of a typical cpu of some kind?

    what about executing an instruction ?
    how does it happen on a multi core cpu? i mean suppose we have a program, how does a cpu know which core should manipulate that program( or thread/ ) ? is it done by operation system or no there is sth in the multi core cpu's which actually do these stuff (when we have a program or bunch of programs which wants or want to execute ,that specific part actually direct them to use core x for example ?

    suppose we have couple of programs which are to execute and awaits the cpu to be executed, are these applications going to be executed on one core ? or they are all eaqually disrebuted on all cores?
    suppose we have 4 programs and we have a quad core cpu , what happens then in this scenario ? are they going to uttelize the whole 4 cores ? or no / ? they would just use two cores (by the help of using threads ) ? or on one core again by the help of (threading on that core)

    i would be grateful if anyone answer any of my questions . or atleast direct me to a place which i can read and find out the information im seeking.
    thankyou in advance
    Highlight Your Codes
    The Boost C++ Libraries (online Reference)

    "...a computer is a stupid machine with the ability to do incredibly smart things, while computer programmers are smart people with the ability to do incredibly stupid things. They are,in short, a perfect match.."
    Bill Bryson


  2. #2
    Registered User
    Join Date
    Aug 2006
    Posts
    99
    Complicated. In most designs, each core is just that, a Separate, Duplicated processor core, all on the same piece of silicon. For most multi-core designs, there is a common, largish, L3 cache, and smaller L1 and/or L2 caches which are generally split into instruction and data cache's.

    Intel's "Core 2 Duo-Quad" processors actually were not, they were (are) simply two separate Core 2 Duo processors mounted in a common carrier, with separate L3 caches.

    Intel's I7 series now is a true quad core processor, all 4 built onto a single piece of silicone, and sharing the L3 Cache, though each processor core has its own local private cache. I7's are also hyperthreaded, which means each CPU can deal with two instruction streams. That makes the I7's look like 8-core processors.

    In any event, it is entirely up the the operating system to schedule processes and threads to run on available cores. The CPU has no actual say in the matter. The Operating system has every right to put all running threads on a single core, and reserve the rest for itself, or ignore them, but that is not typically done!

    Actual computational power is absolutely NOT 'Balanced' among available cores, unless perhaps you are actually running a parallel tasking OS, with parallel tasking programs, but that is not what you will generally find in 95% of desktop processor usage.

  3. #3
    Registered User
    Join Date
    Sep 2004
    Location
    California
    Posts
    3,257
    The cores will each have their own ALU. As far as I know, the only thing that the cores share is the L2 cache (they each have their own L1 cache). I don't know how universal this is; there may be some architectures that share L1 cache, or have independent L2 cache.

    A single-threaded application will not be spread out over all the cores. It will run on one core. A multi-threaded application can use multiple cores during its execution. Which cores it uses is decided by the operating system's scheduler.
    bit∙hub [bit-huhb] n. A source and destination for information.

  4. #4
    بابلی ریکا Masterx's Avatar
    Join Date
    Nov 2007
    Location
    Somewhere nearby,Who Cares?
    Posts
    493
    thanks a billion guys , that helped alot .
    by the way where exactly should i look after the multi core cpu design in Intel's site ? i mean i noticed that bunch of review and benchmariking websites present a internal scheme(or shape) of a quad core cpu (for example )
    where do they get that kind of pictures ? or the info concerning those new architectures?
    Highlight Your Codes
    The Boost C++ Libraries (online Reference)

    "...a computer is a stupid machine with the ability to do incredibly smart things, while computer programmers are smart people with the ability to do incredibly stupid things. They are,in short, a perfect match.."
    Bill Bryson


  5. #5
    Malum in se abachler's Avatar
    Join Date
    Apr 2007
    Posts
    3,189
    It really depends on the specific processor model. Basic Intel processors have 2 ALU's, a dedicated FPU for the NPX and 2 FP execution units for SSE per core. AMD I believe has 2 ALU's but only one FPU which is shared between both FPU and SSE instructions.
    Until you can build a working general purpose reprogrammable computer out of basic components from radio shack, you are not fit to call yourself a programmer in my presence. This is cwhizard, signing off.

  6. #6
    بابلی ریکا Masterx's Avatar
    Join Date
    Nov 2007
    Location
    Somewhere nearby,Who Cares?
    Posts
    493
    thank you very much, i got what i wanted .
    again thank you very much
    Highlight Your Codes
    The Boost C++ Libraries (online Reference)

    "...a computer is a stupid machine with the ability to do incredibly smart things, while computer programmers are smart people with the ability to do incredibly stupid things. They are,in short, a perfect match.."
    Bill Bryson


  7. #7
    Cat without Hat CornedBee's Avatar
    Join Date
    Apr 2003
    Posts
    8,893
    but only one FPU which is shared between both FPU and SSE instructions.
    I believe that newer models (K10) have two FPUs at full SSE width.
    All the buzzt!
    CornedBee

    "There is not now, nor has there ever been, nor will there ever be, any programming language in which it is the least bit difficult to write bad code."
    - Flon's Law

Popular pages Recent additions subscribe to a feed

Similar Threads

  1. Couple of questions about XOR linked lists...
    By klawson88 in forum C Programming
    Replies: 5
    Last Post: 04-19-2009, 05:55 PM
  2. a couple of questions about System.String
    By Elkvis in forum C# Programming
    Replies: 5
    Last Post: 02-17-2009, 02:48 PM
  3. A couple of Basic questions
    By ozumsafa in forum C Programming
    Replies: 8
    Last Post: 09-26-2007, 05:06 PM
  4. Couple of Questions
    By toonlover in forum Windows Programming
    Replies: 10
    Last Post: 07-14-2006, 02:04 AM
  5. couple questions for newb
    By bluehead in forum C++ Programming
    Replies: 10
    Last Post: 11-24-2001, 03:32 AM

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21