On Fri, May 27, 2016 at 11:21 AM, Alexander Duyck <alexander.du...@gmail.com> wrote: > I started out this morning by trying to run DevStack on the latest > "net' kernel and it looks like I am hanging on some sort of locking > problem with RabbitMQ. Specifically I am seeing one CPU jump to 100% > with perf showing that I am spinning on a lock. > > I'm working to bisect it now, but just thought I would put it out > there if anybody had already root caused this issue. Below is a few > traces to the spin lock call on the spinning CPU:
I misread the perf trace. I wasn't spinning on a lock I was spinning on the IOV iterator. It just happened to push the lock to the top of the perf trace. I bisected it down to the recent change in iterate_and_advance which was already fixed in Linus's tree in commit 19f18459330f "do 'fold checks into iterate_and_advance()" right'. - Alex
