[phobos] Sleep(0) vs Sleep(1) for yield

[David Simcha]

  Good point.  I guess maybe a shared static this statement that 
initializes an immutable variable to either 0 or 1?

On 9/5/2010 4:07 PM, Brad Roberts wrote:
> It probably shouldn't be done via a version statement as that's purely a compile
> time decisions.  Runtime would allow apps to choose behavior based on where they
> run.
>
> On 9/5/2010 11:40 AM, David Simcha wrote:
>>   Seems like a no-brainer to me.  We're basically talking about getting rid of
>> workarounds for problems on platforms where the original problem doesn't exist.
>> Thanks for noticing/taking care of this.
>>
>> On 9/5/2010 12:17 PM, SK wrote:
>>> Hello,
>>> Core.thread.yield call has a performance hobbling work-around for
>>> scheduler problems in Windws XP and earlier:
>>>
>>>       /**
>>>        * Forces a context switch to occur away from the calling thread.
>>>        */
>>>       static void yield()
>>>       {
>>>           version( Windows )
>>>           {
>>>               // NOTE: Sleep(1) is necessary because Sleep(0) does not give
>>>               //       lower priority threads any timeslice, so looping on
>>>               //       Sleep(0) could be resource-intensive in some cases.
>>>               Sleep( 1 );
>>>           }
>>>           else version( Posix )
>>>           {
>>>               sched_yield();
>>>           }
>>>       }
>>>
>>>
>>> Microsoft fortunately fixed the problem for new versions of Windows,
>>> starting with Windows Server 2003 as described here:
>>> http://msdn.microsoft.com/en-us/library/ms686298%28VS.85%29.aspx
>>>
>>> On Windows 7:
>>> Sleep(1), the workaround, allows only 1000 thread yields per second
>>> per core, which is agonizingly slow.
>>> Sleep(0) allows 4.7 Million yields per second per core on my 2.6GHz machine.
>>>
>>> Any objection to changing to Sleep(0) for Windows 2003 and above?
>>> What definition is suitable for use in version() to make this distinction?
>>>
>>> Regards,
>>> -steve
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