[PATCH] D37677: [libc++] implement future synchronization using atomic_flag

[Dennis Luxen via Phabricator via cfe-commits]

dennis.luxen added a comment.

In https://reviews.llvm.org/D37677#866362, @bcraig wrote:

> Is there a benchmark where this demonstrates some performance improvement?  I fear that the switch to condition_variable_any will swamp any performance gains from the switch to a spin lock.
>
> Also, the spin lock is being held during allocating operations (the exception throws and at_thread_exit code).  That's a little long to be holding a spin lock.


Thanks @bcraig, I will devise a benchmark and report back with its numbers for X86_64.


https://reviews.llvm.org/D37677