On 10/28/2014 08:12 AM, Andi Kleen wrote: > Alex Thorlton <athorlton@xxxxxxx> writes: > >> Last week, while discussing possible fixes for some unexpected/unwanted behavior >> from khugepaged (see: https://lkml.org/lkml/2014/10/8/515) several people >> mentioned possibly changing changing khugepaged to work as a task_work function >> instead of a kernel thread. This will give us finer grained control over the >> page collapse scans, eliminate some unnecessary scans since tasks that are >> relatively inactive will not be scanned often, and eliminate the unwanted >> behavior described in the email thread I mentioned. > > With your change, what would happen in a single threaded case? > > Previously one core would scan and another would run the workload. > With your change both scanning and running would be on the same > core. > > Would seem like a step backwards to me. It's not just scanning, either. Memory compaction can spend a lot of time waiting on locks. Not consuming CPU or anything, but just waiting. I am not convinced that moving all that waiting to task context is a good idea. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>