title: Can a work-item with bigger global id be executed before a work-item with smaller global id?
body: <p>I read the OpenCL specification and did not find how global id is assigned. Is it assigned in EnQueue time, or is it assigned in running time?</p>
  
  <p>If later, it is easy to see that a work-item with smaller id is always executed earlier or at the same time as (if in a same warp) a work-item with bigger id. If it is assigned in EnQueue time, can we guarantee that execution order is consistent with the global id?</p>