On Thu, 2010-02-25 at 11:53 -0500, Mathieu Desnoyers wrote: > > It would be very trivial compared to the process-private case. Just IPI > > all CPUs. It would allow older kernels to work with newer process based > > apps as they get implemented. But... not a really big deal I suppose. > > This is actually what I did in v1 of the patch, but this implementation met > resistance from the RT people, who were concerned about the impact on RT tasks > of a lower priority process doing lots of sys_membarrier() calls. So if we want > to do other-process-aware sys_membarrier(), we would have to iterate on all > cpus, for every running process shared memory maps and see if there is something > shared with all shm of the current process. This is clearly not as trivial as > just broadcasting the IPI to all cpus. Right, it may require another syscall or parameter to let the tasks register a shared page. Then have some mechanism to find a way to quickly check if a CPU is running a process with that page. -- Steve -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
