On Mon, 10 Sep 2018, Waiman Long wrote:
One major issue with a combined count/owner is that we may have to use cmpxchg for reader lock which will certainly impact reader-heavy workloads. I have also thought about ways to compress the task pointer address so that it can use fewer bits and leave the rests for reader count. It is probably doable on 64-bit systems, but likely not on 32-bit system given that there are less bits to play around.
Yeah we've discussed this before. As a cleanup it would obviously be good, but I fear about raw performance loss when using cmpxchg instead of xadd. Thanks, Davidlohr
