[mdlug] Dual Core with Hyper Threading

[Aaron Kulkis]

David Lane wrote:
> I guess it is like getting a sports car, the things that make a sports 
> car are the performance features.  If you dont use them why did you pay 
> the extra dollars?
>  
> I guess if someone has information about Tweaking and tuning Linux for 
> current technology let me know. 
>  
> I DO know that Intel's compilers are free for Linux. 
>  
> And yes the whole point (or at least one) is that I develop threaded 
> server applications. just knowing that I can squeaze a bit more 
> performace makes spending the extra money for a CPU makes since.  Having 
> the extra performance and not using it is a waste.
>  

In general, threading is a hack for operating systems which have
lousy performance on context-switches (*cough* windows *cough*).

Just use parallel processes with shared memory..your life
(and programs) will be MUCH simpler.

> David
> 
> 
> */"Ingles, Raymond" <Raymond.Ingles at compuware.com>/* wrote:
> 
> 
>      > From: Aaron Kulkis
> 
>      > But fortunately, the Unix model (of which Linux is an implementation)
>      > is fully able to grow with improved hardware with little notice for
>      > the user... or even admins for that matter.
> 
>     Well, yes. And Unix had the concept of multitasking and asynchronous
>     operation from the get-go, which helps when moving to multiple CPUs.
> 
>     However, it's not *quite* that simple. Taking good advantage of
>     parallel processing takes conscious attention and design, at least on
>     the application level. Some problems are easy to parallelize, but others
>     are much harder. (The canonical example is trying to get a baby in one
>     month using nine women...)
> 
>     And some programs can 'get away with' un-thread-safe practices on a
>     single-processor system, but can break badly when run on an SMP system.
>     Effectively they don't bother 'protecting' sections of code from
>     interference by other threads/processes/whatever. When there aren't any
>     other processes running at the same time, no biggie. But if they are
>     run on a multiprocessing system, Bad Things can happen.
> 
>     A few of the standard Unix and ANSI C functions essentially "assumed"
>     one CPU in this manner. E.g. ctime(), getlogin(), the original
>     concept of
>     "errno", etc. See here:
> 
>     http://www.unix.org/whitepapers/reentrant.html
> 
>     That being said, the conversion to 'reentrant' code is essentially
>     complete for Linux and has been for years. The same for the conversion
>     to 64-bit processing (something Windows is still having trouble with).
> 
>     Your point is basically correct, of course, but I figured a little
>     expansion and clarification couldn't hurt. :->
> 
>     Sincerely,
> 
>     Ray Ingles (313) 227-2317
> 
>     "It is as useless to argue with those who have renounced the use of
>     reason as to administer medication to the dead." - Thomas Jefferson
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