[libdispatch-dev] testing tree now ported/automaked and committed

Paolo Bonzini bonzini at gnu.org
Thu Nov 5 01:28:51 PST 2009

On 11/05/2009 10:18 AM, Robert Watson wrote:
> I plan to spend time investigating dispatch_priority today.

FWIW, my testing showed the same problem with this test.

> There are arguments for/against both approaches, but I was pondering
> adding a non-portable POSIX semaphore extension to FreeBSD supporting
> relative timeouts to avoid additional clock reads to convert between
> the two bases.

Computing relative timeouts from absolute timeouts is problematic 
because you never know if the process can be scheduled between the 
computation of the delay and the actual invocation of the wait. 
Computing absolute timeouts from relative timeouts, instead, never has 
this problem.

Since time-fetching syscalls usually have a fastpath on modern OSes, it 
would be nice if libdispatch provided a way to specify an absolute timeout.


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