[concurrency-interest] Lock-free signaling

Joseph Seigh jseigh_cp00 at xemaps.com
Mon Feb 19 06:19:19 EST 2007


David Holmes wrote:

>  
>
>>There's Linux futexes, windows events, and probably some undocumented
>>Solaris interfaces
>>but yeah, a lock and condvar implementation could be problematic.
>>    
>>
>
>Current hotspot implementation is mutex+condvar on Solaris and Linux, and an
>Event on Windows.
>  
>
I once did a lock-free condvar implementation on Linux using the futex 
syscall.  The NPTL version uses
an internal mutex.  I measured a 10% scalability performance 
difference.  That's at least 10%
because Linux preempts signalers and that causes major degradation in 
scalability so the
actual amount of degradation might be much greater.

Hopefully the atomics use native compare and swap where possible. 


--
Joe Seigh


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