[M3devel] ease of switching between pthreads and userthreads?

[Olaf Wagner]

Quoting Tony Hosking <hosking at cs.purdue.edu>:

> On Apr 27, 2011, at 3:05 AM, Jay K wrote:
>
>> About inlining LOCK I was more echoing your past sentiment
>> than giving my own, and I provided a mitigation:
>>  a) specifically the suggestion that the switchability be an option;
>>   it'd probably be on by default but people that want to squeeze
>>   out the extra performance could enable the inlining
>>   and lose the switchability
>
> It is expected that LOCK will be implemented using CAS (and   
> equivalents) in the very near future.  I have a student working on   
> it.  This will be incompatible with the current user-threads   
> implementation of LOCK.  It will be too painful to support both   
> using a compiler switch.

Couldn't we change the existing user threads to use CAS for locks, too,
in order to gain runtime switching of thread implementations?
I have neither thought much about it nor looked at the implementation
in recent years, so I hope it's no stupid question.

Olaf
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