On Wed, Jan 22, 2025 at 02:44:20PM +0100, Peter Zijlstra wrote: > On Tue, Jan 21, 2025 at 06:31:20PM -0800, Josh Poimboeuf wrote: > > > +/* entry-from-user counter */ > > +static DEFINE_PER_CPU(u64, unwind_ctx_ctr); > > AFAICT from the below, this thing does *not* count entry-from-user. It > might count a subset, but I need to stare longer.
Right, it's a subset. Something like so: /* * This is a unique percpu identifier for a given task entry context. * Conceptually, it's incremented every time the CPU enters the kernel from * user space, so that each "entry context" on the CPU gets a unique ID. In * reality, as an optimization, it's only incremented on demand for the first * deferred unwind request after a given entry-from-user. * * It's combined with the CPU id to make a systemwide-unique "context cookie". */ static DEFINE_PER_CPU(u64, unwind_ctx_ctr); -- Josh
