On Tue, Jul 9, 2024 at 7:11 AM Paul E. McKenney <paulmck@xxxxxxxxxx> wrote: > > On Tue, Jul 09, 2024 at 11:01:53AM +0200, Peter Zijlstra wrote: > > On Mon, Jul 08, 2024 at 05:25:14PM -0700, Andrii Nakryiko wrote: > > > > > Quick profiling for the 8-threaded benchmark shows that we spend >20% > > > in mmap_read_lock/mmap_read_unlock in find_active_uprobe. I think > > > that's what would prevent uprobes from scaling linearly. If you have > > > some good ideas on how to get rid of that, I think it would be > > > extremely beneficial. > > > > That's find_vma() and friends. I started RCU-ifying that a *long* time > > ago when I started the speculative page fault patches. I sorta lost > > track of that effort, Willy where are we with that? > > > > Specifically, how feasible would it be to get a simple RCU based > > find_vma() version sorted these days? > > Liam's and Willy's Maple Tree work, combined with Suren's per-VMA locking > combined with some of Vlastimil's slab work is pushing in that direction. > I believe that things are getting pretty close. Yep, I realized that this might be a solution right after asking the question :) I've been recently exposed to per-VMA locking, so I might take a look at this later. > > As with your work in 2010 and MIT guy's work in 2013, corner-case > correctness and corner-case performance regressions continue to provide > quite a bit of good clean fun. > > Thanx, Paul
