On Tue, Sep 5, 2023 at 6:19 PM Marco Elver <elver@xxxxxxxxxx> wrote: > > > Good suggestion. I propose that we keep the rwlock for now, and I'll > > check whether the performance is better with percpu-rwsem once I get > > to implementing and testing the performance changes. I'll also check > > whether percpu-rwsem makes sense for stack ring in tag-based KASAN > > modes. > > I think it's quite obvious that the percpu-rwsem is better. A simple > experiment is to measure the ratio of stackdepot hits vs misses. If > the ratio is obviously skewed towards hits, then I'd just go with the > percpu-rwsem. > > The performance benefit may not be measurable if you use a small system. I started looking into using percpu-rwsem, but it appears that it doesn't have the irqsave/irqrestore API flavor. I suspect that it shouldn't be hard to add it, but I'd rather not pursue this as a part of this series. So I still propose to keep the rwlock for now, and switch to percpu-rwsem later together with the other perf changes.
