OpenCL synchronization between work-groups

Question

Is it possible to synchronize OpenCL work-groups?

For example, I have 100 work-groups every work-groups have only one item (don't ask me why, this is an example), and I need to put barrier to every work-item which ensure that all work-groups will be continue after every work-item in this 100 work-groups reaches this barrier point.

Answer 1

No, you can't. You can synchronize threads inside a group, and you can synchronize kernel executions inside a command queue.

You may be able to synchronize a small number of groups as long as they are all executed simutaneously, using atomic accesses. But it will freeze if some groups are scheduled later, and you have no control on this.