[fpc-pascal] getting started with threads

[Jonas Maebe]

On 18 Sep 2009, at 21:30, Dariusz Mazur wrote:

>>
>> On 18 Sep 2009, at 16:24, Dariusz Mazur wrote:
>>
>>> I use own lockfree FIFO http://www.emadar.com/fpc/lockfree.htm to  
>>> distribute task between threads
>>> its much faster and well scaling on multicore.
>>
>> Note that it won't work as is on non-x86 machines, because it's  
>> missing memory barriers (and I think that you may actually need  
>> memory barriers on x86 too). Atomic operations are not memory  
>> barriers by themselves, and the fact that you perform an atomic  
>> operation does not mean that afterwards all cpu's will immediately  
>> see this new value.
> I don't know other machines. On x86 used atomic operation, as Intel  
> said,  all needed cache are resolved.
> I've made very stress test on several computers. it works good.

At least on PowerPC it will fail (and I guess on SPARC as well).

> Algorithm is very simple, need only 32bit CAS, thus implement it is  
> possible on most platforms.
> One thing is needed: multiplatform threadswich.
>
> I use sleep(0) ,but its not best solution (I think).

At least on Mac OS X that will not do anything. There's a procedure  
called "ThreadSwitch" in the interface of the system unit though. At  
least for Unix platforms it will work if cthreads is used.


Jonas