On Apr 26, 2014, at 5:36 PM, Jens Alfke <j...@mooseyard.com> wrote: >> OS X implemented GCD at kernel level which introduced lots of syscalls which >> are super expensive. The old school method is largely user land so it may >> help a little by keeping syscalls to a minimum. @synchronized uses >> Objective-C runtime functions which was once code behind those old school >> classes. > > That's the opposite of what the docs say: "A dispatch semaphore works like a > traditional semaphore, except that when the resource is available, it takes > less time to acquire a dispatch semaphore. The reason is that Grand Central > Dispatch does not call into the kernel for this particular case. It calls > into the kernel only when the resource is not available and the system needs > to park your thread until the semaphore is signaled.” —Concurrency > Programming Guide
They say this for dispatch semaphores, but it doesn’t necessarily apply to dispatch queues. (If I were less lazy, I suppose I could check the source.) _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com