Hello, On Mon, Jun 09, 2025 at 03:56:10PM -0700, Shakeel Butt wrote: ... > + self = &rstatc->lnode; > + if (!try_cmpxchg(&(rstatc->lnode.next), &self, NULL)) > return; > > + llist_add(&rstatc->lnode, lhead); I may be missing something but when you say multiple inserters, you mean the function being re-entered from stacked contexts - ie. process context, BH, irq, nmi? If so, would it make sense to make the nmi and non-nmi paths use separate lnode? In non-nmi path, we can just disable irq and test whether lnode is empty and add it. nmi path can just test whether its lnode is empty and add it. I suppose nmi's don't nest, right? If they do, we can do try_cmpxchg() there I suppose. While the actual addition to the list would be relatively low frequency, css_rstat_updated() itself can be called pretty frequently. Before, the hot path was early exit after data_race(css_rstat_cpu(css, cpu)->updated_next). After, the hot path is now !try_cmpxchg() which doesn't seem great. Thanks. -- tejun
