No objections. :) Reviewed-by: Axel Rasmussen <axelrasmussen@xxxxxxxxxx> On Tue, Nov 26, 2024 at 11:29 AM Roman Gushchin <roman.gushchin@xxxxxxxxx> wrote: > > On Mon, Nov 25, 2024 at 09:16:17AM -0800, Shakeel Butt wrote: > > We are starting to deploy mmap_lock tracepoint monitoring across our > > fleet and the early results showed that these tracepoints are consuming > > significant amount of CPUs in kernfs_path_from_node when enabled. > > > > It seems like the kernel is trying to resolve the cgroup path in the > > fast path of the locking code path when the tracepoints are enabled. In > > addition for some application their metrics are regressing when > > monitoring is enabled. > > > > The cgroup path resolution can be slow and should not be done in the > > fast path. Most userspace tools, like bpftrace, provides functionality > > to get the cgroup path from cgroup id, so let's just trace the cgroup > > id and the users can use better tools to get the path in the slow path. > > > > Signed-off-by: Shakeel Butt <shakeel.butt@xxxxxxxxx> > > Acked-by: Roman Gushchin <roman.gushchin@xxxxxxxxx> > > Thanks!
